I think the Dance games have emerged to take the spot of the old Music/Rhythm Games genre.
On Topic:
There is an issue with how funding from publishers have only backed certain ideas about FPS but COD and Battlefield have been around since before this gen. It must be companies that are trying to carve out some marketshare and think they must adopt COD elements in order to standout or be successful. Killzone 2 transition to Killzone 3 comes to mind. Heck, look at Uncharted 2 to Uncharted 3's multiplayer.
As for single player, microtransactions have been stated as the future. and it's much more cost effective to give you 5 maps for 15 bucks than to bring out a extra two-three hours of single player experience. So, of course, companies are going to try to break into the multiplayer market.
But, I believe that overall, the OP is corrrect.
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