It's a hard question. At least on the home console market, Sony and the PS4 havea stronger grip on the industry than MS and Nintendo combined, so they're not in a hurry to change their hardware. I'm sure Sony will be the last one to introduce their new systems, they need it the least. And, opposite to the PS3, they're getting tons of profits from the beginning. I doubt the Vita will get a succesor, though. Maybe it will have a lifespam similar to the GameBoy, but if there's someday a Vita 2, it will be a mobile phone with buttons to game on.
I keep watching Microsoft trying to go for a bigger share of the PC market, and that will affect the XBone. I know the XBone is the fastest selling console of theirs, but if MS thinks it's easier and more profitable just fighting for PC dominance over console dominance, I doubt there will be a XBtwo.
Nintendo will update their hardware soon, maybe for a more powerful system or for something as powerful as the PS4 but cheaper. I hope the Fusion idea gets done, but I don't know the kind of tech they would need to make it happen.
Only Nintendo needs to update soon, really. Whether is the PS4 dominating as it is or the XBone getting less and less atention from MS in pursue of PC, this will be an interesting gen.
