For those who move to locations with less rent and less cost of life, the company and the employee should split the difference. Moved from a place where average rent is $3k/month to somewhere it is $1k/month? Employee keeps $1k/month, company pays $1k less, everyone is set. Same for cost of life.

Everyone should make an opportunity out of this. It shouldnt be so that 'You moved so this is a great chance for us to reduce the cost you mean to us'. That's not only unproductive and demeaning, but it also exposes the rotten mentality of the current economic system.