1. Nintendo
2. Microsoft
3. Sony
I really think near the end we'll have a few years of a Nintendo and Microsoft rivalry on the level of Sega vs. Nintendo back in the day. I don't think Sony will make it through all of next-gen and I truly believe PS4 will be their last console.
At the very least, I know the Vita will be their last handheld. The thing's really on it's last leg and once the Triforce of Monster Hunter 4, the next Dragon Quest, and Pokemon Gen 6 hits 3DS, it'll be over for Sony in the handheld space worldwide.
I also think people are really underestimating the power of Wii U. PS2 was the weakest technically of its era but went on the become one of the most successful consoles of all time. The first year of Wii U is really what is going to shape next gen. If the third-parties investing early support do well, I think a lot of the late current-gen third party stuff currently in development (Bioshock Infinite, GTA V, MGS: Ground Zeroes, MGS Rising, Lightning Returns, Star Wars 1313 and Watchdogs) will make its way to Wii U. None of those games are UE4 and if developers see they can continue making money and innovating on tech that's cheaper, they will for as long as possible.
Microsoft will become the go-to "tech-powerhouse" console and get the most support from Epic and the guys working on UE4.
Like I said, a repeat of the Nintendo vs. Sega days: a weaker console with more early support (Wii U) vs. a beefier console with strong third-party ties (Durango).