The political price for repealing the ACA may be very small. The 20 million with coverage from the ACA is vastly over-stated. 10M from Medicaid expansion, some from the growth in the economy, some from shifting from the individual market to the exchanges, some from the mandate. Plus, for some, it's a crappy product, hence the issues the exchanges are having.
According to Democratic orthodoxy Republicans only represent, due to gerrymandering, white evangelicals. If true maybe the political hit is small. And to suggest there will be no market for insurance once the ACA goes away is really just silly. Unless, of course, legislation bans new products from being offered.
There will be a hit; no one knows the magnitude. It would be ironic if the impact were as large as what the Democrats suffered for passing the law in the first place.