I dunno, I guess I just think TOS should be good enough on it's own without having to pull from later TNG+ material. It's fine with cameo appearances, but as a major antagonist? The Borg again?
By the time Star Trek 2016
hits theaters, it'll have been twenty years since the Borg were seen on the big-screen.
For the 50th Anniversary, I'll imagine they will want to put on a show.