It's hard to speculate what Trump might do. I'm reasonably certain that most of the people (not all, but probably most) who work for him think it's a horrible idea and will work hard to stop it. But I'm sure he feels the desire to do something, and that worries me. I mean, sometimes he does go out of his way to pick the option people don't think he'll do (pulling out of Paris, pulling out of TPP, bombing Assad, etc), other times his more moderate aides and underlings seem to win out (recertifying that Iran is compliant with the nuclear deal, hasn't built a wall, not pulling out of NAFTA, etc.). I mean he can try and sink Obamacare in a number of ways: the most likely is to just "let it fail" as he has promised, but he can also take very active and immediate steps that would instantly send the markets into a death spiral (such as stopping certain subsidies, or not enforcing the mandate.) The problem is that the latter, while more effective, also dramatically increases his culpability in the "failing" part, and most Republicans are very, very aware of that. On the other hand, if the Senate hands him a bipartisan fixes bill, what does he do with that? Would he oppose it? Would they veto? Who even knows.