I agree with you that this is an unfortunate mindset to have concerning retiring. That said, how many Americans realistically will have a sufficient asset base as to think in these lofty terms you describe? Some will, yes, I don't deny that - but the vast majority? Leave the US on a retirement visa to a lower cost country - or work until death or at least much longer than you would have to if you departed the US.
In this scenario, how many will stick around in the US? It will be interesting to see to be honest as this reality is playing out now as we speak and given the givens, I can't see it not intensifying going forward. Rob