Let’s assume that stablecoin usage grows massively. Everyone everywhere has easy access. 

People in countries where the currency is less trusted will move lots of money to stables. 

What happens when these less trusted countries lose control over their local currency?

There’s a reason why these countries have less trusted currencies/systems/govts.

In these places they will simply ban economic exchanges in any currency other than local, so big moves such as in real state or transportation will still provide demand for their shitcoins.

The only thing that comes from this is people might actually shield themselves from political-economic flaws, preserving some of their purchasing power which, at the very bottom of the line, will sustain a bit of the demand for local currencies.

Power will still rule. But ppl will benefit at least.