I think the next-gen could be the repeat of gen 6 in the sense that PS4 will be the most successful system and outsell the X1 and WiiU by a wide margin just like PS2 outsold the Xbox and GameCube by a wide margin.
Even in games terms, it seems the X1 and WiiU are trying to give a Xbox and NGC vibe. (hardware is in favour of PS4 this time around tho)
But on the other hand, Sony does seem to have a more new IP focused line-up which could actaully be a disadvantage in sales terms. (because more people prefer established franchises)
Also, the X1 is trying to combine gaming with broader entertainment and WiiU still has a "family appeal" so I would not write them out, as possible successful products.
What do you think - are we possibly looking at a new (or re-defined) gen 6?