The FPS's are the big sales hitters, and as such they get a lot of media coverage and marketing, but if you just look at the games coming out, the other genres are doing fine, releasing great AAA games. Look at RTS's: the Total War series, it's doing great, The Command and Conquer series enjoyed a very successful run for well over a decade, and came to the end of its story.
RPG's: Skyrim is coming in November, Fable is a strong franchise, as is Fallout, and Bioware have made their company successful almost exclusively through great RPGs.
Speaking of Bioware, they are in charge of the new Star Wars MMO, which has had the majority of their resources poured into it.
Sports games are trundling out sequels with a new player list and slightly better controls for a few decades now, and that juggernaut shows no signs of slowing.
Even 3rd Person Stealth games are fine: Splinter Cell has been going for about a decade, AssCreed has really taken off, and there is a new Thief Game.
Heck, you could say that FPS's are getting diluted to become more like RPGs, with the idea of including "RPG elements:" Upgradable guns and armour, Halo Reach had customisable character skins, as will Brink (In a big way) And CODs multiplayer is based on an MMO style leveling system, kill 5 men: get a perk. Get 1000 points: level up - You can now use uzis.
Just because developers realised they can quickly squat out an FPS with a 5 hour rushed campaign and a multiplayer mode ripping off the previous successful title, with a few minor changes, and rake in on the current fad, doesn't mean that other genres are stagnating.
