WWE would have him back in a second, they might of got him over but get over he sure did, and was more popular than Cena for a good while. Plus he had huge pull with women demographics which no other male wrestler really has (maybe they tune in to see Orton's abs or something, idk)
As for his drug problems, he was pretty reliable last time he was under contract with WWE. Sure he got suspended once or twice but nothing major as Victory Road shambles, which is totally on TNA for being a bush league company and sending him out there on TV in that state.
As long as he's jumping off tall shit, I can deal with him popping a few pain pills, as crass as that sounds I'm only interested in him entertaining me, not being his social worker. He can shoot up all he wants in his hotel room for all I give a shit.