Pretty much everything you're all saying about next gen was true this gen, and Xbox didn't even come close to coming in first. It didn't even outsell the PS3 all that much, even with the year lead.
IMO, Sony's biggest problem was launching at $599 and having few compelling games, all while the 360 was in its 2nd year (usually the first good year of a console). And PSN just wasn't ready. That won't happen next gen. No way are PS4's launch and design going to be mishandled that badly. And PSN now has the basic features most people expect--I really think much more would just bells and whistles that might be nice, but won't really affect sales much. If (a) they perform as strongly as they did in the latter part of this gen, and (b) launch effectively and on time, they could end on top.
But I don't think Wii U is going to go nearly as well as the Wii did, because Nintendo seems to have abandoned its 2005-2007 philosophy and the customers it brought into the fold. All the worst pathologies of that company are coming to dominate product development again. Thing is, Nintendo has so far to fall that it could still come in first while drastically underperforming expectations.
MS also suffered from severe launch problems that seemed to prevent them from doing better than they could have. I'm guessing they've figured out that you can't launch hardware without thorough testing and then just expect to patch it later. So they will fix those problems. But their plans to expand have been typical Microsoft--add more checkboxes to the product specs. And none of their big plans have resulted in explosive growth. So I don't see them in a bad spot, but I don't see why I should expect them to lead. Their barely-beating-Sony-for-second-place thing mainly happened because Sony screwed up so, so, so, so badly, and I don't think that's going to happen again.
The end story is I have no idea who will "win."