If they bring in an in-game LFG I'd consider buying this because matchmaking, as DX pointed out, would be rather difficult since communication is key to doing a raid successfully (yes even Crota requires communication even if it is easier then VoG).
Even a new campaign isn't worth going back for since you could honestly beat the original campaign in a couple of hours if you set the time aside to do so (I think in total you could do the entirety of Destiny Vanilla in about 3 hours, 4 if you actually took your time). Plus the trailer, with what little story it gave away, didn't look all that impressive (outside of the new subclasses) and they really need to do an expansion dedicated to the Cabal because I'm sick of Vex, Hive, and Fallen. I really want to know more about the Cabal since they're the odd man out (you only get one planet you deal with them on where as you get 2 for every other race (3 for Fallen)).