Below is an evaluation of how all of my current builds will fare in the new paradigm. The order is that in which I created and leveled each character (but I left off Guardian because I only recently started it). At the end I will tally the survivors.
Warrior
WvW/PvE: I'm not supposed to discuss the details of my WvW guild's builds, so let's focus on my one true love, the shout healing cleric. I traditionally run a 00662 build with mace/shield and hammer. The first two lines are still to be ignored. In toughness, the shield unification is likely one of the best unifications announced; I've made PvP builds using all three former traits. I used to take last stand and cleansing ire, but that would no longer be possible under the new system. This forces me to either run a stability utility (thus less shouts) or use trooper runes for condi cleanse (the clear choice). But the most frustrating choices are the grandmaster slots. I love mainhand mace in PvP as much as anyone, but that grandmaster trait is almost entirely PvE focused. Endure pain is rather underwhelming for a cleric compared to a zerker. Perhaps I'll take rousing resilience if the heal scales. In the fourth line, I will obviously take both shout traits. With the open slot I'll take leg specialist with little enthusiasm, though it will net kills for my peeps with hammer shock. And the opportunity to max discipline is not actually that promising for this build- warrior's sprint is great and all, but the master and grandmaster traits are mostly inconsequential (even the hammer one). Perhaps I should revisit the first line for a death from above component.
> Conclusion: Alive, but less optimized and with fingers crossed for the elite specialization to save the day.
PvP: I currently run an axebow roamer with a zerk amulet built around eviscerates that always crit. Now that grandmaster trait has been moved to the arms line, completely changing this build. I must choose to give up either strength (vitality and axe damage traits), defense (survivability and adrenaline building), or discipline (versatility and burst damage). Seems I'll have to give up the strength line, but it will likely be compensated by the endure pain grandmaster and damage from the Arms adept and master traits.
> Conclusion: Alive, but a bit different.
Ranger
WvW/PvE: This is tricky because my favored build, Beastmaster, has been dead since June 25, 2013. My most recent revival attempt is 04253 with a greatsword and shortbow and I've tried all kinds of stat combos. So how might I build a beastmaster in the new system? The former best pet line, Skirmishing, has seen its pet traits scattered elsewhere. Wilderness Suvival can be ignored as well. The first line now has some interesting traits, particularly the new GM (predator's onslaught) that will benefit from control skills. The fourth line has a critical minor (fortifying bond) for a pet build, but the non-adept traits add nothing. The decent pet traits from nature magic have been moved into the beastmastery line, but other than the new taunt it's hard to get excited.
> Conclusion: Still dead, unless the extra pet stats from the new nature's wrath trait are amazing or druid revives this build concept.
PvP: I run a spirit build with sword/torch+shortbow and a settler amulet. He's dead, Jim. You know the difference between a stationary spirit and a turret? The latter has high health, toughness, is self-healing, and damages those who attack it. Spirits never had any defenses except that you can move them; there are no traits to bake in. Now they'll be AoE cleaved down instantly. RIP
> Conclusion: Dead. But on a more positive note, I'm looking forward to exploring other non-bearbow builds.
Elementalist
WvW/PvE: I run various formulations of an offensive staff build. This build will be nerfed in its versatility because it uses components of fire, air, water, and arcana. Basically I'll have to pick between fire and air, neither of which are particularly appealing if I have to fill them with three traits (and I could say the same about arcana). I'm going to have to rethink staff ele from the ground up and perhaps go with earth magic.
> Conclusion: Alive, but considerably less versatile.
PvP: I run an offensive staff build with a celestial amulet. In contrast to my WvW build, this build readily goes all the way into fire and may improve overall by dropping arcana for either air or earth. But I'm not sure if celestial will still be best after its announced nerf.
> Conclusion: Alive, but may need to adapt to a new amulet.
Mesmer
WvW/PvE: Recently I've been working on a zerg mantra interrupt build, 06620 with soldier stats. I found the early results encouraging (though my WvW guild shit all over the build). The first line would be interesting if they up the chances that dazes will become stuns as suggested in the stream. Consolidating mantras in the second line doesn't really open up great possibilities in that line. Probably not worth going all the way into the third line for immobilizing. Can't get mender's purity in the fourth line without going the whole way, so condi removal is now an issue. Basically this build would have to be reimagined as either an offensive power block build or as a non-dps healing build.
> Conclusion: Dead, as a balanced soldier build.
PvP: I use a wonky but effective phantasm build (22064) with glamours and a knight's amulet. It also features three adept traits in one line. With the trait changes, the first line is still required for the adept illusion damage with no benefit from the rest of the line. Similarly the fourth line would be required for its minors with no surplus benefits other than mender's purity. The fifth line has one minor and one major worth taking for phantasms, but otherwise it's the same story. This build would be highly unoptimized.
> Conclusion: Dead. Guess it's time to learn shatters (or rack up some PvP mesmer wins).
Engineer
WvW/PvE: I run a zergbusting gadgeteer build with pistol/shield and soldier stats, 20462. It's hard to say exactly what will happen given the state of engi traits, but there are some concerning signs. The movement trait, now "robo legs," has been moved into the second line with little other benefit there. The gadget trait will be required, but the rest of that line looks unappealing as well for this build. On the plus side, this build already had several blast finishers, so the new engi healing is intriguing. Ultimately this build is in a similar place as my mesmer in that it will likely have to pick either offense or healing to move forward.
> Conclusion: Given the state of engi traits, I'm going to pronounce this build Alive for now, but it will have to change considerably.
PvP: I run a defensive turret build with pistol/shield and a sentinel amulet. Turret consolidation should benefit this build highly with the opportunity for more healing in the third line. I'll probably still use the fourth line for more survivability. This still leaves the first line available to buff the new mortar elite kit or blast on dodge. Wow.
> Conclusion: Alive, and likely to come out stronger.
Thief
WvW/PvE: I run a zerk d/p gank build to ruin the day of EotM K-trainers, 06404 with stealth features. Moving executioner line from the second to the first will shake up this build, de-emphasizing flanking but allowing for panic strike. But now as I analyze the third line it appears my favorite thief trait, Hidden Thief aka stealth on steal is being removed. I see there's now blinding powder on stealth in the fall damage trait, but this is not equivalent- foes can tell when you release blinding powder, and they'll dodge before I can activate backstab. But with Hidden Thief most fools don't even realize I'm there before I backstab. You've got company now Proven in your thief disappointment.
> Conclusion: DEAD. I don't care if the concept of my build is the exact same as that of the thief class itself. They've removed my favorite trait so my build is dead.
PvP: Thief is my worst pvp class. I've tried d/p which makes me feel one-dimensional, p/d which is somewhat effective but completely noobish, and sword which makes me feel too vulnerable. I'm still upset about Hidden Thief so let's just move on.
> Conclusion: Alive, for the sake of the final tally.
Necromancer
WvW/PvE: I run a power build with 100% crit chance in death shroud, 62006. With the 2 of the second line (well ground-targeting) being baked in, this is a straight buff to power necros, allowing them a whole new trait line. The fourth line will probably win out due to the well grandmaster trait, with a nice buff to necro mobility via the master dagger trait.
> Conclusion: Alive and better than ever.
PvP: I run a similar 62006 power necro build here but with two spectral skills. The shift in the fifth line allows the new condensed spectral trait in addition to the essential death shroud traits; this is huge. On top of that the whole third or fourth lines are available for new options. Nothing to complain about here.
> Conclusion: Alive and the sky's the limit.
Overall
Alive: 9/14
> Alive with expected improvements: 6/9
> Alive but must adapt to survive: 3/9
Dead: 5/14
Do not interpret my identification of dead builds as condemnation of the new trait system. Change is inevitable. The only things I'm disappointed in are the lack of a clear cleric warrior build and the removal of Hidden Thief.