If you think about this from a game theoretic perspective, it makes business sense to "defect" first (make this offer to employees). If all firms could be trusted to cooperate, they could pressure workers to return and workers wouldn't have any recourse. But because the first firm that defects has its pick of the remote talent litter, the slower you move the worse off you are.
Not really. Most _good_ companies are really flexible for employees they value a lot in terms of remote work, so this is not an issue. And they will likely have contingency plans to go mostly or fully remote in case they realize they are losing too many people.
I'd actually be curious to see an analysis of this. All of my experience suggests that there is indeed a significant difference in employee quality and a substantial cost imposed by turnover, but I'd love to see some data to the contrary, i.e. that the "employee as interchangeable cog" model is defensible.