I mean, let's face it, they're bleeding money right now, and they're probably going to bet everything on this console. The PS4 will need to have a PERFECT launch to give Sony even a SLIGHT chance of avoiding bankruptcy.
While it is possible, Sony's games division isn't what is in trouble. We will see Sony go through a restructuring and they will lose some of their divisions that are the problem soon. So, while possible for PS4 to be the last, I think it is unlikely.
It's possible for any of the big three to have their last consoles next gen. Sony weren't even meant to exist beyond 2006 on this board. --- NP: (PS2) Suikoden III (PS3) Mass Effect Trilogy (Vita) PSABR (PC) Gothic (Wii U) Xenoblade (360) Nothing lately
Sony's problem is that they have a large, confusing product (e.g., they have something like 3 different TV product lines) line for their other devices. What we are going to see is Sony streamlining their other products which I think will give them a better market position. The PS4 will have to perform well to keep the game division up and running, but not the company as a whole. --- PSN: Samhain2057