Doesn’t matter what infighting killed of which regime. The end result is massacres, purges and violence that killed off or destroyed the lives of hundreds of millions. No wonder such criminal ideology is dying its own death. Even in ex-communist countries evolving into something else including China and Vietnam.Prove it. Take my 19,500+ posts and prove it.
Pol Pot's system was dismantled by Communist Vietnam.
The DRPK of the Kims has free housing, I think free public transport and generally free healthcare. Though yes, dynastic rule is not Socialist or Communist. I wish that DPRK adopts the actually Communist Jamahirya Direct Democracy system that governed Libya until 2011 and that has been adopted by Socialist Venezuela by the late Hugo Chavez.
Another Communist country Cuba has one of the best, if not the best, healthcare systems in the world. It's healthcare professionals have rendered humanitarian services around the world.
How it is to be brought about depends on the society / country.
How it is to be sustained, well, Jamahiriya Direct Democracy political governance, progressive, evolved and just economic system like the one I proposed ; progressive social system ; technological advancement ( ideally ecology-respecting )... why would any sensible person not see their benefits ?