We’re not talking about moving from a local office to remote office in another country, which is historically what outsourcing meant. We’re talking about having literally no tangible difference between the same (or directly equivalent) worker living in a HCOL or LCOL area. This is what will very clearly and predictably lead to the erosion of salaries.
But then what's the issue with that? There's no real reason that a job should be deemed worth more/less in different areas. If someone decided to live in Kensington and someone else in Bexley (googled cheapest place in London to live), there's no reason they should be paid differently.
Presumably it would then lead to a balancing of property costs around the UK (if taking the UK as an example), as there would be less of a premium attached to London based areas as the salaries would be equal no matter where you lived. You'd effectively be balancing what a job was "worth" rather than inflating/decreasing it by non job related factors. The same as a loaf of bread costs the same in a Tesco in London as it does in a Tesco in the poorest areas.