The only part that I'd argue is that the PS3 didn't really struggle to achieve parity. It outsold the 360 during most of its lifetime and by a pretty nice margin. I know what you're saying about total sales but sales rate is just as important. It's a marathon instead of a sprint, after all. It showed that the Playstation brand was stronger than the Xbox brand during this generation.
That being said, the PS3 was kind of lacking as a device. It had quite a few faults which I really hope they improve on. If you remove the exclusives from the picture, the 360 is probably the better console (though it has faults, too).
What the PS3 did have, which made it special, was the support of World Wide Studios. WWS, in my opinion, is the life's blood of Playstation. I think they're the best group of developers in the world, and Sony is the best publisher. WWS rescued the PS3 and lifted it up.
If they can get the console part of the PS4 right, and I think they can, then World Wide Studios gives them a great shot at the top--and that's not even to mention all those yummy third-party exclusives.
