It took a literal world war with hundreds of millions dying to establish the first successful state-wide communist revolution, with mass global impoverishment, at a time when most migration, even for the wealthy, was done by train.

The conditions that are fundamentally missing is that all of these areas are fundamentally isolated, so if one has the means to revolt, it is easier to use those means to hop on a flight and leave. The issue is mostly that there is still too much global surplus that can be dealt out.

Ultimately we are in a position where there is a global international bourgeois that, through its various connections, pretty much runs everything that is important (water purification, fuel refining, finance, major agricultural products, entertainment, etc.) and a working class that is barely even conscious of itself. It will take some major disruption, or likely a series of major disruptions, thst weakens the grasp of those in power. The issue still, of course, being that that global international bourgeois loves a good crisis, if it can organize around it and profit from it.