nintendo 40%
sony 30%
MS 30%

I think Microsoft will carry fifty five percent of the market share. Sony will carry thirty percent of the market share, and Nintendo will carry fifteen percent of the market share. Unlike some I will explain my reasoning with a concise listing of decisive factors. While I think previous trends are important. I think what is offered is what will be born out in the final analysis. I am going to skip the expounding this time around, because this thread is pretty fast paced, and I want a quick read, but I will be more then willing to expand these points if someone would like.

Microsoft
1. Has twenty one first party games/entertainment studios. More games, and original content equals more sales.
2. Has the best casual interfaces, and is developing augmenting technology, and is already truly universal.
3. Has the greatest cash reserves, revenue streams, and the will to use them to cut price points, overcompensate on hardware, or to acquire assets mid generation.
4. Has a lock on as the next edutainment device. You thought Master Chief and Mario were monsters. They are nothing compared to the sales power that is Dora the Explorer. Especially if one of Microsoft's entertainment studios streams truly interactive children's entertainment.

Sony
1. Has downsized its stable of first party studios down to thirteen. That isn't enough to support both the core, and the casual market place.
2. Doesn't have a single promising casual interface, and hasn't displayed any new technology to replace, or even to augment its existing technology.
3. Has severely depleted reserves, questionable revenue streams, and is dependent on loans to fund acquisitions.
4. Sony isn't in a position to expand its demographic base in any meaningful way. Though over the past few years it has done a competent job of tending to its current player base.

Nintendo
1. Hasn't really increased or decreased its stable of studios, but it still hasn't managed to diversify what those same studios offer. The platform is still fundamentally kiddy. Nintendo is basically the least dynamic of the players.
2. Nintendo has managed to create a cumbersome interface, and worst of all it discourages family interactions around their games. They have created a one player system. Nobody else is even contemplating that.
3. Nintendo has decent cash reserves, but has failed to capitalize on them to address long standing problems.
4. Nintendo has actively decreased their potential audience. They abandoned their core to lavish attention on the new casual player base. Now they have abandoned them, and are trying to court those core players. Who for the most part have probably switched brands for good.

Basically I think Microsoft is too strong, and is too well diversified to be denied yet again. It doesn't just mean that they are going win. They are going to win by playing the whole field simultaneously. Sony will probably retain a large portion of its current player base, because Sony for the most part gave them what they wanted. Nintendo will end up however losing badly. The only thing they have going for them is a severely depleted player base. The truth of the matter is they squandered a generation where they could have built up a diverse portfolio of new franchises, significantly improved their infrastructure, and remade their image while they were front and center. Instead they are coming into this generation with the same problems they had going into the last, but with one big caveat. They don't have a fad to hang Mario's hat on.

55% huh, are you on gametrailers by any chance?

Look at the front page and look How casual games have been doing this year on MS. Nintendo owns that part and will keep it. Sony will have more IPs than MS. 

Ridiculous.

No one continues to buy products that fail. Ask anyone who has purchased a car. Utterly absurd notion. People lost a lot of confidence in MS after that, next generation will prove it. 

As I said though, it will be quite close, but MS, again, will not win a generation.

Sony will gain market share back, there gaming department is one of there stronger sectors there not just gonna kick back and get pushed out.

wow @ ppl downplaying Nintendos offerings again .. 'here we go' again(mario voice) ..

Sony and MS should be the same as this Gen...fighting for the same place.. ALL depends on how much their next hardware costs.. but they always be sharing the same users LOL!

Nintendo will dominate all if they keep their pricing low compared the other two.. PRICE is the BIG factor nextGen not whats inside! keep that in mind you noobs!

MS will not take hits in order to expand the brand, they have shareholders to please. They did that this generation and are in a great place moving forward. There is just no justifiable reason they would take another hit when it isn't necessary. It will be profit above all next generation.

55% lmfao. Well, we'll see but this seems absolutely absurd. 

It's because there are no indicators that the Wii U is setting the world on fire, at this point.  Many believe, myself included, that when the PS4 and NeXbox come out most 3rd party support for it will dry up within a year or two.  While the Wii had its motion gaming to fall back on, it doesn't seem like the tablet controller is going to be that huge of a draw.  And I know many fans think Nintendo's 1st party will help it still be #1, but 1st party didn't save the N64 and Gamecube from falling behind Sony.  Of course, the PS4 and the NeXbox will be more expensive then the Wii U (I'm guessing they launch at $399-$499), so we'll have to wait and see if people feel the price is worth the better graphics or if they'll flock to the Wii U because its cheaper.

The fact Sony came back from the dead (sales wise, but not profit wise) pretty much guarantees Sony has the potential to hold on to or increase market share next gen. But it comes down to execution.

My out of my arse guess is that each of the big 3 have a hardcore fanbase of around 30-40 million. Everyone else is the democratic equivalent of a swing voter and will go where the perceived value and enjoyment is greater.

Im gunna go for :

Sony: 39%
M$ : 34%
Nintendo: 27%