Salary will be mosty based on value one adds.

Not just tech salaries, but any job that can be done remotely. Caveat: Companies pay what employees are WILLING to accept, not what the job pays. Workers with lower wage expectations always get paid less, regardless of locale. But locale has a big influence on what people expect.

I have made most of my money the last ten years re-writing software created in India. I have realized that executives will keep failing the 'mythical man month' test and chasing cost over speed and quality and keep me in business as long as I want do this.

One of “pretty interesting effects”, as you call them, is the fact that youngsters don’t want to be anything but remote workers. This results in the massive shortage of critical workers.

Nope this will never happen

I still think time zones are gonna matter a lot here.

Some talents don't know how much they are worth and companies are taking advantage. Also even companies are taking advantage, a dev in Latam o Africa, for instance, is making 5 times the local salary. It's complex

Depends on the timeframe. I think they are going to become more equal, but not equalized. Since even in most remote companies, there is a price to pay for teams located in wildly different timezones.

We really need some “tax tech” products for all of digital nomads. Does “digital nomad tech” industry actually exists?

Doubt it. Lots of companies are not ready for remote work. Besides that, are you going to fire your high performers that are paid high salaries and replace them with lower wage remote workers? I don't know anyone willing to make that gamble.