I understand that. Such a proposal cannot be introduced on a given day and applied to all. It can only be a slow implementation done over say two generations.

I understand that. Such a proposal cannot be introduced on a given day and applied to all. It can only be a slow implementation done over say two generations. People would need to see it coming, take that into their understanding and calculations as they move towards it. In other words, grandfather clause would need to be there. https://en.m.wikipedia.org/wiki/Grandfather_clause https://en.m.wikipedia.org/wiki/Grandfather_clause