I wouldn`t say that this gen will be unsustainable for Xbox 720 and PS4 to the point of one of them leaving, but seeing as it will be the first time both MS and Sony will release both consoles at the same time (PS2 came first and then Xbox 360 came first) it will make a dent on both consoles.
This time neither manufacturer will have time to gain awareness.
Overall, i think PS4 and X720`s biggest obstacles will be PS3 and Xbox360.
These two consoles have great catalogues and will have lower prices. More if it`s true that Kinect will como bundled with X720 and Dualshock 4 is revamped, than the prices of the consoles will go up.
My prediction is that prices will go from 350 to 450 - most likely 400/450.
If this happens and prices go up for games than the adaptation rate for both consoles will be low. Why? For 1 or 2 years developers will support PS3 and Xbox360 giving them few reasons to run and pay 400/450 for a new gaming console to play games they can have on older, cheaper consoles.
And given that both consoles seem to have high tie ratios, buying games will be more affordable on PS3 and Xbox 360 than on the coming generation.
Wii U is facing what will probably be it`s dark period in all of it`s generation. Honestly, better facing it now than when the other two consoles arrive.
If Nintendo can get it`s act together after March with Zelda and another big hitter for the Christmas period (probably Mario Kart) and then a flow of 1st and 3rd party titles following Christmas, then it`s all set to do what 3DS did.
