Doesn't being playable in WWE's game mean he already signed a contract?
I'm not sure about that. Wasn't RvD in Smackdown vs Raw 2011 while he was in TNA?
I know he had a contract signed before, for the WWE 2k15 game, where he's part of the promotion of it (which includes being in the trailer obviously). That wasn't a talent contract though.
Nothing official on the talent contract but I'm gonna go ahead and say that they have one in place and/or agreed and signed, as of the reveal of that trailer. Cause they started selling official Sting shirts on the WWE shop after that promo aired, and I doubt they'd start selling merch if they didn't have something already in place as far as the talent contract goes.