Outsourcing already happened without salaries equalising. To the extent that it can be done, it has been done. For instance, I have a constant stream of people on LinkedIn wanting to sell me projects in eastern Europe and India.
I think the thing to think about is how negotiating positions change. On the face of it you'd think it's bad for Western devs because there's more competition. But it's also bad for hiring managers because there's more of them competing too. I recently had a remote offer gazumped by another one, which would not have happened in the days of "all finance jobs are in a London office".
For people in the low income countries, they have the double edged sword of low cost of living. OTOH they can live like princes on a western salary. OTOH they have to give up some of that because anyone bargaining with them knows they will share a large chunk of the excess in the form of a lower salary. You can cry "same work same pay" all you like, they will agree a lower salary themselves.
There's also a eye of the needle effect. If someone had been a FAANG or similarly hard to get role, people are going to want to pay them more, just because. Similarly if someone hasn't worked in the west and gotten paid in the west, people will negotiate lower pay for them. This is really awesome if you were a FAANG guy whose family is Indian, you'd get a top % of the world income in a middle income country. But for most of the unanointed, it's good but not great.