Yeah, the PSR-S900 came out in the summer of 2007, and Yamaha usually replaces models every three years. The one exception that I remember was the PSR-2100 coming out a year after the PSR-2000, and the PSR-3000 coming out two years after that, but the PSR-2100 was almost identical to the PSR-2000 it replaced. I think it only had 12 additional voices and maybe 6 new styles.
It also occurred to me that the recession might slow down the introduction of another keyboard.
Beakybird