a) No complete overhaul of the U.S. healthcare system is going to happen before 2021 at the very earliest anyway; and
b) Regardless of what the hypothetical overhaul ended up looking like (M4All, Med4America, or a Public Option), it would likely take a couple of years of going through the legislative and regulatory process before actually going into effect; and that therefore...
c) In the short term (i.e., the next 2-3 years at least) what we should really be focusing on is protecting, repairing and strengthening the ACA itself, via a robust ACA 2.0 bill package.
As I reminded folks, there are two excellent ACA 2.0 bills which have already been introduced in both the House and Senate, with many overlapping provisions: In the House, it's H.R. 1884...which has also in turn been broken out into about a dozen smaller, standalone bills (several of which have already passed through the full House). In the Senate, it's S.1213, the Consumer Health Insurance Protection Act or CHIPA. As far as I know, the Senate version is a single package bill and has not been broken out into smaller chunks.