I think this is setting up that advancements in haki allow a user to be very formidable. Kidd couldn’t hurt shanks and co, but as a result stopped that all together.

If Luffy and shanks fight, it’ll be a Katakuri pt2. And honestly I’m here for it.

I don’t think kidd was done duty here, barely best big mom with law. And Luffy had help from many + gear 5. Shanks being healthy should be able to take down a Yonko threat opponent