The industry seems to be talking more and more about WiiU this year, one console in 2013 and one in 2014. Since we know quite a bit about MS next console but vertually nothing about PS4 (at least nothing I've seen) I think it's fair to assume that PS4 would be the last to market.
I do think that has a lot to do with PS3 only recently becoming profittable. PS3 will not have the legs of PS2. PS4 will kill it pretty quick. PS2 was a MASSIVE seller and even an 80% drop in sales was still a worthwhile system to sell. PS3 may be on top right now, but it's on top of a saturated and dropping market and it's own sales are falling y/y. Bottom line, unlike PS2, PS3's sales will be too low to maintain within a year of PS4 launching.
Launching last isn't great but it's not necessarily bad, as you can see what the competition is doing and capitalize on that knowledge (to some degree). You can also come out with something that's innovative and distruptive, putting the ball firmly in your own court. However, this is Sony we're talking about....







