I don't think anyone can afford not to bring it.
Nintendo - According to analysts the Wii U is under performing and I know it's anecdotal but from what I saw it was only supply constrained for the first few weeks if that which is never a good sign. If they want to move hardware they are going to need killer software. While I am sure they will have some success with first party software like the new Mario Galaxy equivalent, Mario Kart, Smash, and Zelda, I don't think they have enough in house development to afford software droughts like in previous generations.
They need to get 3rd parties on board and fast with original software and enhanced current gen ports but this doesn't seem to be happening. DQX and Monster Hunter may move some hardware in Japan but I don't think the system will be successful in the West. I think 3rd parties are transitioning from current gen to next gen and Wii U is a current gen machine so it won't get much support at all.
Sony - All signs point to MS launching this holiday, if that's true then E3 is going to be their big coming out party. If Sony is not unveiling a next gen hardware platform then they really are in a tough position and will lose E3 by default. They won't be able to generate a whole lot of excitement for the PS3 with all the fanfare over the next gen Xbox.
If they do unveil PS4 and they launch at the same time or after the Xbox they have to persuade consumers that their platform is worth buying instead of the Xbox and even worth waiting for. They are going to be scrutinized about specs, system features, backward compatibility, software, online infrastructure, and every other little thing. Is Sony ready to leverage what few advantages they have over the competition? I'm not confident they can go head to head with MS and steal the spotlight.
There have been so few rumors and leaks about PS4 that I am more inclined to think won't be launching this year.
MS - They have momentum right now and if they beat Sony out of the gate that will carry them cause they'll have a full holiday season advantage. A lot of what I said about Sony and going head to head applies to MS as well, they are in direct competition for the same audience.
I'm not convinced MS is going to be ready to launch this fall either. A quality current gen game takes about two years give or take, so how long does a quality next gen game take to make?
I think MS is in a dangerous position because they have aspirations for the living room and that could cause the hardcore to abandon the Xbox platform if they don't feel like they are being catered to. I mean look at their press conferences, they have been awful for the last few years, they simply aren't speaking to the core audience that made their platform a success. I am all for Kinect 2, but if that device is packed in and as a result increases the price of their already presumably expensive console it might be a smart move long term as far as support for it goes but it could open the door for Sony.
PSN has almost achieved feature parity with Live and offers a great pay service in PS+. Live is going to have to up it's game if they want consumers to keep paying for it and they will need to make some changes to the platform as a whole. The indie community has a lot of issues with the current certification and patching processes on Live and as a result the advantage that Live Arcade had in the digital space is gone. I also feel like Sony does a better job of cherry picking interesting indie games to bring to their platform in the latter half of this gen as well. Will MS be ready with a truly next generation Live platform or will they release an even shittier version with more ads and more cluttered menus to wade through before I can get to what I want?
I'd say the biggest thing they need to worry about though is the Steambox because they are competing for the same market. There is a lot of overlap with the software libraries and if Steam provides a universal experience of purchasing once and playing on both the Steambox and PC platforms then they are going to take a lot of marketshare from MS. That goes for Sony to a lesser extent but for many people either platform wouldn't offer a real value other than for exclusive titles which will be few and far between even more so next gen.
It's going to be a bloodbath this gen, with dev costs going up both publishers and console makers have almost no room for error. They have to compete with each other, and devices like the Apple TV and probably something from Google sometime during this next gen in addition to Valve. When the dust settles I don't think Nintendo will be in the console hardware game, I doubt Sony will, and MS really can't afford any major missteps if they want to stay on top.
Thats pretty much bang on my opinion on them as well. Definitely agree that Sony will have to throw themselves in if they want to take back first place in the West, they made some bad choices in the wake of the PS2's success and the run up and first year of the PS3 that have worked against them the entire generation. They've started making headway the backend of the generation, especially with PS+ being a major win for them, but they need to get the benefits out there to the general public and keep momentum going.
On the other hand, I do feel MS have been losing ground lately and basically making the same mistakes Sony did between the PS2 and PS3 and getting too comfortable, as there does seem to be a build up of people turning away from them due to MS turning towards the console being an entertainment system and beginning to lose focus on gaming ,and the Live system. I've started noticing there is a general feeling that people feel they are held hostage by XBL because its where all their friends are and paying for online rather than added value, and with the rise of PS+ actually showing what a subscription can offer, if Sony push that hard on PS4 and during E3, they could have the rug pulled from under them.
Nintendo I think have the most to prove. The casual market that made the Wii what it was just hasn't been there so far for the Wii-U, and the abandonment of the traditional Nintendo fans with the Wii and the under-powered (compared to what the next Xbox and Playstation are likely to be) won't win them back by simply being Nintendo and I don't think the current 3rd party support will be able to help them. They really need to push the first party stuff, and hard, and definitely need to show a plan that there will be that support for more than a year or so like there was with the Wii by frontloading Mario Kart, Smash Bros and Galaxy in the first year and a half, then near enough nothing until Skyward Sword in its final year. I think getting a steady stream of Nintendo titles out alongside getting developers on board with the likes of a new Last Story, Xenoblade and Pandoras Tower early on, pushing them hard (and actually releasing them globally asap) and keeping that support running is possibly their best chance.
Edit: Although, I disagree on Nintendo and Sony being gone once its all over. Nintendo I think still have the ability to coast as they are. It won't do them good, but they're still able to do it based on the Japanese market, much like they did the N64 and Gamecube. It took Sega 2 1/2 completely unsuccessful systems to finally kill them, Nintendo are far better positioned to just keep going. Its not going to win them any awards, but I don't see a coffin yet.
Sony I think are even safer, I think America is the odd one out when it comes to its popularity. the PS brand is still going strong over here in Europe, even though Xbox is the frontrunner there is a lot less distance between the two, and from everything I understand its still the leader in Japan, so unless the other Sony departments screws things up so badly that it hits the Playstation side of things, I can't see them being taken down either.