@OP:
I'd say really too early for each one, HD consoles are too expensive to develop, so they need more years as top level model to recover initial investments, while Wii rules so easily that Nintendo can do what it wants and Wii2 release will be decided by Wii1 sales trend and HDTV market penetration.
So, IMVHO:
XB720: 2012
PS4: 2013-2014
Wii2: ?
But what's for sure is that Wii2 in 2010 is plain ridiculous. The only concern for Wii is current Japan sales, it would be crazy to send Wii to early retirement everywhere else, it would kill almost sure huge future sales of a product with a fabulous profit margin there, hasten Wii2 development raising its costs and lowering its performance and features/price ratio and all this most probably without solving the only problem.







