If the foundries can pull off 2 die shrinks in the next 5 years (we already have one coming in the next year, so one more after that), plus stacked ram and other advancements in actual chip design, and I can easily something along the lines of a Titan level of power (or even a decent amount better) being able to be had in next gen consoles and fitting into both the power and price requirements that MS and Sony would lay out. Now the question of whether they'd used that power to do 4 times the resolution, or just make things prettier at 1080p, depends on where 4K TV adoption goes in the next couple of years. It looks like the prices will be coming out of the stratosphere on them as early as next year (you can buy well known brand name 4KTVs now for around $2500, so next year could easily see them getting to around $1000-1500), and if they can get the prices to around $500-700 by two or three years from now, then I can see them getting enough penetration to make console makers target them. But that's a pretty large if.
LG's new line of 4K TVs start at $1500, and Samsung is coming out with some cheaper models (HU6900 series) in the coming months. It's really only Sony that is keeping their prices sky high on 4K.
That's why I say, by next year, most people shopping for a new TV will be going 4K whether they want to or not. 1080p is going to be phased out on everything but the cheapest models.