Rebirth is predicated on the idea that DC screwed up with its handling of the New 52 revamp and is trying to course correct by appealing to old fans while also trying to not alienate current ones.
How on Earth would obviously teasing the return of the classic Wally West, then failing to deliver on that accomplish any of those goals?
It's Wally, and he was a founding member of the Teen Titans. Period. Will he be sticking around after Rebirth? Dunno. But you are crazy if you think this is a fake out.