The problem is not consoles evolving, it is that they do not evolve fast enough. The idea is that a box can be designed that will last for 5-10 years with the developer recouping huge initial losses over the entire life of the system. This idea is dead. Look at the difference in performance between this year's smartphones and last year's. Or over two years, three years etc... If you want a concrete comparison fire up Infinity Blade II and compare it with headlining games from 2-3 years ago on the 360/ps3. That was the mid-point in that generation's life-cycle. It was never anticipated that the gap between a console a phone would close so quickly. It was also not anticipated that stationary and mobile consoles would converge (like the Wii replacement tablet thing).
Give me a device that I can use as a mobile console (and that I will actually carry as does other stuff with the pocket space it occupies), and then give me an easy way to plug it into my tv and use it just as a controller on a big screen. We are not far from that point now, and the pace of improvement in the phone business and the short window between release cycles means that by the time it is feasible for Microsoft / Sony to bring another generation of consoles to market - there may be no point. Combine an iPad with AirVideo and it is already a good replacement for a console as a multimedia device.