So I think in the end they can vote to end the mandate. THAT will give Trump something to say "I won." Of course it changes nothing substantively about the HC markets.
It would be a MAJOR change, the majorest possible (is that a word?). Because Obamacare was based on forcing everybody into it, and ignoring people's own opinion on whether a hugely expensive Obamacare plan with crushingly high deductibles, was right for their own particular situation. The mandate was a classic example of liberal elites thinking they know better than their subjects, what was best for them... and forcing them into it even if they disagreed. The Mandate represents everything government should NOT be, but frequently is... under big-government tyrants.
If just the mandate is repealed, suddenly people are free to choose whatever health plan is right for THEM. There will be growing pains, because that mandate crushed out of existence most of the plans that insurance companies used to offer, leaving only the few that conformed to Obamacare's dictates (remember "If you like your plan you can keep your plan"? That's how big a lie it was). But those insurance companies can quickly dust off those old policy plans and reinstate them, and design a few more for situations those didn't cover.
And a few million people can wave money in their faces and say, "I want a plan that offers this and that, and doesn't offer the other thing, and if you have such a plan we'll give you all this nice money. What do you say?". That's the kind of thing that can get companies to work hard to please the people and get all that nice money. They can negotiate, make some counter offers, and if enough people like their counteroffers, that money starts to sparkle.
None of those things were possible under Obamacare. In fact, they were
forbidden, on pain of paying penalties all over the place. Obamacare destroyed people's freedom ("for their own good", as socialists and other tyrants always say). Repealing "just the mandate" would restore that freedom.
And for people who like their Obamacare plan, the insurance companies are free to keep offering it. But people might be surprised when they find out how much such plans really cost, once the plans have to compete with viable alternatives .