Well, we still don't know the price points. I think once they're set it will be a huge indication of how the next generation will play out.
There's also still the chance for colossal blunders in the form of RROD type situations with early hardware, or massive marketing errors.
Then the launch exclusives, we know MS has Halo, but what sort of Halo will it be? Has Sony anything big ready for the first two years?
I think the uptake of the new hardware may be a lot slower than this generation. Both of them need to show something compelling to get consumers to jump. At the moment the old consoles are still offering a huge amount of content. My guess as to why Sony went the route of really pushing the SSD is that they felt the visual jump alone was not enough, they'll try to market the instant loading, fast paced, netflix type of gaming approach.
I could well be wrong, I'm hoping to be dazzled by the upcoming game trailers and I'm curious can they offer something in the form of the leap we saw this generation to open world. That was a major selling point, suddenly most games no longer had to be linear.