Do you think Wilder will have a new costume during walkout or will have a robe only?
Most probably we won't see that heavy suit that he wore last time, that's the reason he lose

Lets imagine Wilder looses - will he retire after two straight losses or no?
IMO, he should continue fighting if he wants and just consider Tyson Fury his kryptonite. In boxing, "styles makes fight" so let's just assume that Fury got his numbers. We can't deny that Wilder is one of the feared champions in the heavyweight division and almost all of them have losses so nothing to be ashamed of, it's just one have to lose.
He'll probably go for a simple costume for this fight a simple robe with a lot of embed on it, and if he losses the fight I don't think he will he has a lot of pride and is still capable of knocking out an opponent and no boxer will quit when he is still in the height of his boxing skill, he'll probably deny losing if he losses by decision and if it is by knock out he'll plan to avenge his loss, whatever happens here in this fight he's still one of the most feared boxers in this generation.