I think there's gonna be the same amount of bosses, but spread accross different raids, rather than being in different wings of the same raid like naxx was. It really just gives us more choice. Some guilds could also choose to do 1 on 25 player and 2 on 10 player, or whatever. It will also help pugging, if you only want loot from a certain boss, you no longer have to wait through 8 other bosses to get to it. I for one like this change.

But yeah, if we as a raid group can clear 11 bosses in one night, we are gonna be left doing a bit of thumb twiddling... Hopefully they release lots more raids as patches come out...