It will likely be a year or two. Destiny lacks enough content to be successful on the PC.
From what I have read that is my opinion on it as well. It seems like it cannot decided if it is a game like Borderlands or something more like an MMO. From what I understand is that the game does not run on a server like an MMO but rather you run in your own world or join others and people can join your world freely. I could be wrong the the whole thing seems a little weird to me.