“He needs a workable Trumpcare first, doesn’t he?”
No actually he wouldn’t as by then nobody or almost nobody wold be on ObamaCare anyway.
But since you asked - He has a health care proposal on his website. He does have a replacement
I've read it. Some of what he proposes already exists and the rest won't help lower income families afford health insurance. Plus it's contradicted by some of his public statements. So I don't think he does have a workable plan.