Republicans were entirely unable to end the ACA, despite majorities & the Presidency. Its latest enrollment period saw a massive sign-up. The likely scenario coming up near-term, is Democrats take the Senate & possibly the Presidency (not the House). Healthcare will see gradual stapled on improvements that basically guarantees everyone coverage. Each time the Democrats acquire majorities, they'll put more pieces into place. It's most likely to start out as guaranteed catastrophic coverage for the middle & lower middle class (poor people already have free healthcare), that's the next logical step from the components the ACA put into place. It'll be a messy process, that will ultimately end in guaranteed coverage (most of the top 1/4 will keep variations of employer coverage that provide various perks). As each of these pieces get put into place, Republicans will find it nearly impossible to take them back away from people (as we just witnessed, it was wildly unpopular when Republicans tried to get rid of denial of coverage protections for pre-existing conditions).