I think your prediction is off a bit.
Here's how I see it playing out:
WiiU - Has stumbled out of the gate, much like the 3DS. However, Nintendo was able to quickly address its discrepancies, and cut the price, which has made it rather viable. I don't see this happening with as great success with the WiiU, as the competition will be much more fierce, and its opposition is going to bring far more assets. The WiiU will become pidgeonholed over the next 2-3 years as getting ports of 360/PS3 titles, while seeing an increasingly skimpy 3rd party library, as its hardware shares little with its next-gen kin. Additionally, their online infrastructure and digital footprint is the weakest of the three, which puts them in a very precarious situation with publishers that are constantly seeking more value and revenue from long-tail sales via the digital market place.
It will sell between 30-45m units LTD.
PS4 - Sony has done arguably everything right with its release. However, they're dealing with something they've never faced before: Less brand awareness, and a competent opponent in Microsoft. They've made a very smart play for developers and publishers, which will help them out considerably this coming generation. Additionally, their online push is likely to yield some strong value going forward.
However, I think that the one thing that will hurt them this time is the same thing that hurt them last gen - price. It may not be as significant as the abysmal $599 of yester-gen, but its still likely to be very unfavorable when compared to the next Xbox. However, they'll see a generation that is far more fluid than the last one. I believe they'll sell in between 70 million and 90 million units worldwide.
Nextbox - Its hard to fully speculate on the system, as we only hear rumors. However, Microsoft is also in an odd position: The driver's seat, or something close to it. They added 50 million users this generation, while their heated rival lost 50 million. They're seemingly adopting a very general gaming focus, as they are likely to push both core and Kinect. This could either be brilliant, or awful. The hardware is likely to be underwhelming compared to the PS4, but is likely to be competent enough to get the same ports as the PS4. Hopefully, the architecture is easy to work with, allowing for affordable exclusivity and other deals the coming gen.
What will really separate Microsoft, good or bad, this coming generation is online features and entertainment. Microsoft destroyed Sony and Nintendo when it came to their online offerings - XBLA titles destroyed PSN and WiiWare by hefty margins, and DLC did very well, alongside all of their other noted offerings. They've also added some IPTV functionality, and cable offerings.
The real what-if scenario is if Microsoft can score big next-gen in regards to online and entertainment. If Microsoft can make the next Xbox a set-top system that encourages people to use it instead of AppleTV, Roku, and other devices, as well as push for differed payment options via its X360 subscription model, it could absolutely kill Sony in regards to price and value. Imagine the next Xbox releasing for $199 or even $99 via an XBL Gold subscription model. If they did this, it would nullify any advantage Sony has, and utterly destroy the WiiU's supposed value immediately. But again, these are major "What ifs".. Microsoft isn't stupid, but they aren't brilliant either - they just happened to be the least stupid of the Big 3 last gen. They may sell anywhere from 70 million to 120 million units, depending on how smart they are.
SteamBox / OUYA - I think these consoles are going to be boutique affairs, but they're going to do better than the other also-rans we've seen in years' past. OUYA is likely to sell >1 million units, and a Steambox can probably do 5 million, or so. However, I just don't see them getting major traction, as the other consoles will be just too attractive to develop for. However, they can likely get great affection from indie developers, which may allow them to compete with Microsoft's set top box desires. We'll see.
Back from the dead, I'm afraid.
