Last edited by Sicktight; 2013-10-22 at 01:14 AM.
The answer to the OPs question is: YES.
However - assass is a much easier spec to play than both Combat and Sub and it has the best AoE of all our specs. So assass remains competitive and precisely because it is so easy to play it is not a poor choice for progression (since you can focus on mechanics). Personally I enjoy Combat and Sub more after such a long spell of assass dominance.
I really don't think this is a fair answer. There isn't a blunt yes or no when some encounters still require Assassination mainly due to positioning and uptime requirements - Particularly Paragons of the Klaxxi. For this case, sub is practically unplayable and Combat would be an unorthodox choice due to the little boss time you will actually find in the event of soaking Aims Etc.
In an 'ideal world' where everything is patchwerk or cleave encounters then i would agree that yes, Assassination has slipped off. But realistically its far from being dropped simply due to 'it does less damage' because... well, it doesn't in T16 boss encounters.
On single target all 3 rogue specs are doing quite comparable DPS.
If you are getting wildly different single target dps when changing specs, it is probably because you are not playing it right - or your gear is not optimized for that particular spec.
Also it is kinda silly to say that you are forced to drop assassination - you can pick any spec in the game and do more than enough DPS to "earn your spot" in a normal Raid - possibly even in a heroic raid.
Usually the problem with DPS performance is in the PLAYER/his skill, and rarely in the spec.
Honestly after finishing the tier, If you have access to an AoC and combat weapons, combat is the correct spec on almost every fight that is relevant.