The shit is already built, they need a system admin to keep it running. If those devs were smart enough they could do this transition transparently , you could continue login with your email/password but for some reason management wants this, this is someone project , instead of creating something new and good they move shit around.

It's a shame the people you say are working to maintain the infrastructure are so disconnected from the users that they are satisfied with it being, to quote, "shit."