It's not that there are a 'few Japanese developers that are really trying and keeping it alive'. The system is very much alive in Japan. It's huge there. Didn't it recently beat out 3DS sales despite the fact that the 3DS has only been out for like a month? It's only in the west that it appears to be dying.
It did beat out the 3DS, and the article I read said it was due to the release of the FFIV collection.
That always made me lol a bit. It seems like everytime a big game in Japan is released it drives hardware sales nuts. Who doesn't have a PSP over there at this point that would want one?