DC’s don’t-call-it-a-reboot is the perfect opportunity to give Wally West a costume that’s recognizably The Flash, but different enough from Barry Allen’s costume that even a casual reader can tell them apart at a glance, even if the artists miss a few details. Especially since several elements of Wally’s new costume from Flash: Rebirth (the raised yellow outline around the chest circle, and the V-shaped belt) have been incorporated into Barry’s new outfit.
Yes, I’m talking about the Dark Flash costume, worn by Walter West, a version of Wally from an alternate reality. It wouldn’t have worked in the post-Crisis continuity because of what the experience meant to “our” Wally (he didn’t want to be reminded of what he could have become), but in a revised history, it doesn’t need to have the same associations.
Brighten it up again, make it crimson and gold (like Wally’s current costume), and I think it’ll do the trick.
Assuming, of course, that DC has a place in the New DCU for an adult Wally West, and has neither erased him from history or reverted him back to Kid Flash. (I’m trying very hard to stay positive here.)