If this happens (which I highly doubt), Senate Democrats had better fight tooth and nail to filibuster any attempt at repeal/watering-down.
At which point Republicans will become so annoyed that the filibuster will be history.
Which would be a wonderful thing....although with a catastrophic effect in this particular case.
Yeah, it's pretty obvious that the Republicans are going to abolish the filibuster the second the Democrats try to use it for anything important, which is why the Democrats should just beat them to the punch and do it now.
Also, I'm not convinced the GOP will fear political backlash if they control the trifecta in 2017. They already constantly screw over many members of their base by doing things such as denying the Medicaid expansion and refusing to set up exchanges, and they don't seem to mind. Remember that West Virginia story about how poor whites there wouldn't sign up for Obamacare because they feared death panels and national ID microchips being implanted into them? It's not like these people are going to care if Obamacare is repealed, in fact they will celebrate it as a victory for muh freedom.
This is why it's imperative to have a Democrat win the 2016 election. By 2020, it may be too ingrained to remove, but even that's not certain.