A problem with waiting to see how well Nintendo sells. If WiiU was selling amazing neither competitor could stop Nintendo by launching their new hardware for at least a year. Developers need 6-8 months to get software ready (ports/multi plat) final kits need to be issued with a few months to finish its games.

Retailers need to be notified and marketing campaigns need to be planned.

This is not something you can do on the fly. Neither competitor could wait to see how Nintendo performs. So it would be Spring 2013 by the time MS/Sony know how well Nintendo is doing. Earliest final kits would be available by E3. A winter 2013 launch would be the earliest possible launch. Microsoft could not wait and if Sony reveals their console this year early 2014 would be the latest possible date.

Depends on when MY and Sony decide to releaes their next consoles. If they wait it out too long, like a couple of years or more, they can really start to close the gap between their sales and Wii sales, but the flip side of that is they may have already allowed Nintendo to built up a head start and sales gap with Wii U too large to ever surpass. And what is the point of closing in on Wii sales this late in the game? You already have all the third party support if you're Sony and MS so nothing will change there. So I think they won't wait long to release their next consoles, maybe a year tops. But I guess during that year, you can say Wii U will be competing with them, as it will likely be similar to them in power and recieve ports of HD console games.

@Joelcool7:
Why do you think MS/Sony will come out with new hardware just shortly after WiiU? And why spring 2013? My guess is that Sony might be last out (again) but not more than half a year - probably not even that. I haven't read a rumor that NextBox is hitting the stores in early 2013... I agree, it would make a lot of sense to launch it this holiday, or at the very latest holiday season 2013.

Nothing I've heard points to a spring 2013 release...

I'm just curious to how you're thinking :)

That's right.  It's like trying to pluralize The Lone Ranger...

I personally feel they will. Nintendo is walking on very thin ice. Nintendo is trying to court the 3rd parties, but ultimately every 3rd party game for the next two years will have to be built for the 360 first since that's where their userbase is. Nintendo also has to try to convince those people playing PS3/360 to switch over and ports from the 360 won't do it. Nintendo needs to launch out hard with Mario and Zelda if they want people to switch over right away and a few key 3rd party exclusives (Which they won't have). The key problem is that by the time devs start utilizing the Wii U to the point that the 360 and PS3 can't keep up with, will be roughly two years. Though I'm not a decision maker for Microsoft or Sony.

Personally, I believe it will be announced at/by E3.

no.... and probably not.... to the topic that is..... Wii's brand momentum is dying, so calling it WII u was a mistake

What about GTAV on the WiiU?  All it would need is around 1m copies sold WW to make it a profitable endeavor for Rockstar, given how easy it is to port 360 games to WiiU (not to mention possible incentives from Nintendo).  And having it in its library would benefit WiiU greatly.

the wiiU will be like elizabeth olsen....the youngest of the three olsen sisters that no one remembers.

If momentum was worth anything, the PS3 wouldn't have been in 3rd place all this time, if at all, on the back of PS2 momentum.