Success for a console in the videogame industry is heavily influenced by expectations of success; being that games take a long time to develop, and you have to choose the platforms which will give the best returns on investment based on projections on how it will perform. We have already seen how this can impact platforms being that the PS3 received much stronger third party support than its sales justified, and the Wii received much weaker third party support than its sales justified, primarily because people expected the generation to turn out quite differently.
Being that we’re now 3 years into a generation and somewhere between 40% and 60% of all consoles that will be sold this generation have already been sold most people are expecting the generation to end in a similar fashion to how it stands today. What this means is that the necessary cornerstone for a PS3 comeback (a steady stream of high profile third party exclusive titles) is not going to happen and therefore a comeback is remarkably unlikely.