I liked the old days where each class had a place in the raid, they just knew. A pally/druid/priest/shammy healed, end of debate. A warrior tanked, just how it was.. Everyone else DPS'ed as a certain spec.. "and for a time this was good.
I'd like to show you lots and lots of players who disagree with the good comment. ;) Especially healers who would rather be a different spec to dps. :p
I think they could easily implement more than just two specs, and I think they might at least eventually (probably not right away). Maybe add them in like bank slots/gbank tabs with the more slots you have the more you pay. I think this will be an important feature that raiders as well as pvpers will need to evaluate and submit good feedback on. Now we get to wait for the PTR and other blue notes.