#1 Sony
#2 Microsoft
#3 Nintendo
Sony has the highest chance in my opinion of taking the crown next gen, cuz they know what it takes to be on top from the success of the PS1/2, and they know what it is to be last with the PS3 and that is something they will learn form and try not to repeat, the 360 will always be behind as it barely gets sales in japan and no matter how well it sells in the US it can not compensate for Asia region.
As for Nintendo, allot of people cite that people will simply transition over to the next Nintendo platform, but this mentality only applies to core gamer install base, and not the casual one, it's been proven that the casuals are NOT moved by graphics, so a simple graphics boost will not make the casuals mover over, neither will new enhanced motion controls, I've said it before and I'll say it again, Nintendo's gonna have a very hard time selling Wii HD to the same market unless it's something radically different. Lets face it, Nintendo sold the wii with a gimmick, a hook to catch the casuals, and it worked extremely well to the point of being copied, but it won't work again as allot of the casuals like moms and pops will look at Wii HD for example and see it being identical with the wii they have and see no reason to upgrade, which is why Nintendo will either find a new gimmick and risk all to be number 1 again, or simply end up last.
I also know allot will say that the next wii has to do good, because it's doing good now, but the same thing said about Sony when they launched the PS3 after the extremely successful PS2?
Point is, no one can predict the outcome of the next generation, but we can have interesting discussions with a bit of common sense and a bit of logic thrown into the mix today.
anyways that's my 2 cents thrown in.