I think on the part of Microsoft and Sony (and possibly Nintendo) there will be a lot of emphasis placed on 'downloadable content' - whether it be entire games or overpriced horse armor/etc. - because that is what gets them the most money.
I don't think Sony will try to be as bleeding edge. In fact, if Nintendo keeps doing as well as they are now, I see the other two trying to imitate what nintendo is doing (motion sensing/pointing, not-so-bleeding-edge hardware, casual-friendly games)
Nintendo has learned that innovation is the key to winning in each market - so there will probably be something about the next console that will be akin to what the touchscreen did for the DS and the wiimote did for the Wii.
I'll probably just keep playing my computer games and possibly buy Nintendo's console (if it uses physical media for games). I've been losing interests in consoles over the years - the market is quickly approaching over-saturation point...
