Answer to your (rhetorical) question:
How would we prevent a 2-tier system from decaying to the state that it (supposedly) did in the USSR?Well, one way is to remove the Repos from power.
Their so-called Medicare "reform" is specifically designed to do exactly that: create a two-tiered system so that wealthy seniors get better care, anf the poorer seniors get diddly.
(Now, before Beep busts an artery, and to pre-empt a series of strawmen arguments, it is entirely possible that the Dems' would come up with a similar plan. But we don't know, do we, because the Repos have effectly shut off any access the Dems might have to the decision- and legislation-making process. We don't know what the Dems would do, we do however, know what the Repos will do. So you can put your red herrings back into the pot....)