Yeah, I know what you mean, but it also kind of makes a bit of sense since there's been about a 6 year difference between Sony consoles. For example (and these are North American dates):
PS1: Released 9/9/1995 (9 months earlier in Japan)
PS2: Released 10/26/2000 (7 months earlier in Japan)
PS3: Released 11/11/2006
Notes:
-While a lot of mainstream/popular/good games for the PS1 were released during the 2000-2002 period, the last game for it actually was released in 2005.
- The PS2 was being still sold and supported as of 2009.
I'm kind of saying that it's about that time if you look at the schedule that Sony would think on producing or working on another console. With that being said though, they'll likely produce, make, and push out a lot of super-anticipated PS3 games for the first year or 2 until they've got a steady lineup of PS4 games after launch.