On the subject of how to evolve Halo as a game, it needs to go back to basics first. Its original core resembled Quake, a battle for map control, power weapons, and power ups. The timing of these things is what made Halo so unique, they forced the player to have to think about a variety of things, risk vs reward, no other shooters really did that other than Quake, then it was Halo, then maybe you could say Gears of War tried it but it wasn't the same.
As for abilities being put into the mix of Halo, I would study Shadowrun for the Xbox 360. SR was a good mix of blending counter-strike-style modes/buy system with a unique approach to decision making in an FPS. You basically built your own character within the four races to choose from, per match.
Every ability in SR basically had a sacrifice of some kind, otherwise it wouldn't have been balanced.
For example, the Elf I believe had the most essence (magic juice) for casting spells like teleport, gust, ghost, rez, healing trees, etc. You had to decide what to use your essence for, i.e., if you carelessly teleported all over the place, you would be drained of your essence, and come the situation where you really need teleport during a fight, you may or may not be able to use it due to draining your essence and not giving it enough time to re-fill.
It's tough to explain Shadowrun's gameplay design to people who haven't played it, especially through writing. The point though is Shadowrun's abilities had risk vs reward associated with all of them.
If Halo is to do this, e.g., sprint, there needs to be more risk other than your downed shields don't recharge if you're sprinting. Instead, sprinting should cause your shields to go down, that way you gain an advantage by essentially punishing yourself. It's like rocket-jumping in Quake, you don't just rocket jump without getting hurt (unless you're playing Clan Arena, rocket jumps don't hurt you), you decide that you're going to take the penalty of losing health/armor to gain a high advantage or to out-juke someone during a fight.
I could go on and on about this, but Halo could easily have abilities incorporated into the game and they would be perfectly fine, but they have to associate risk vs reward to all of them. The jet pack for example...shouldn't just give you away on the map or make a really loud noise, it needs to do something else to penalize you for choosing to use it.
I highly doubt 343 will do this though.