So the fear is wealthy people relocating to tax havens? What else is new?
I doubt many Bitcoiners will fully relocate to save on taxes -- and even if, their economic impact will be infinitesimal compared to what wealth is already hidden off-shore both by private individuals and international cooperations. Not to finger-point, but rather to show that there's a deeper underlying problem that has nothing to do with crypto.
Millions of citizens who have found wealth in poorer countries will be demanding high-quality goods and services, meaning they will become even more valuable and their prices will go up.
Is this sustainable?
I doubt that "millions of citizens" in poorer countries will find wealth by speculating with cryptocurrencies. On the other hand if that wealth comes as a side-effect of increased economic output due to increased economic freedom than that wealth increase is merely a reflection of aforementioned output increase.
It's an interesting way to point out though that the current way of living in most developed nations seems to require some parts of the global population to live in poor conditions. It all boils down to winning the geolocal lottery. A kinda shitty system, is it not?