I think most of the Republican replacement plans for the ACA are some version of health savings accounts. Lots of variations around that, and why, as you ask, are Republicans "proposing none of them prior to replacement?" I can't answer. I suppose its the same reason the Dems proposed a few versions of their plan (at least one in the Senate and at least another in the House)-because there is rarely unanimity of opinion and they come to a compromise through the legislative process.
I think the ACA was dying anyway, it looked like it was in a death spiral. So yes, it's going to die, either organically or with an assist.
And of course the Republicans will blame the Democrats. Politicians are masters of shifting blame. But hasn't the country already done this? Isn't that blame a major reason for the House, Senate, Presidency, governorships and state Houses going Republican?