I think it unlikely that the MM program will change at all. Covid and PQPs vs miles flown have slowed down the making of new MMs and the members who were advantaged by the merger are getting older and less likely to be in their peak flying years.
It is probable that the numbers were much more impactful pre-covid and pre PQP than they are now. In my small sample (3) observations, the MM program has boosted loyalty and purchases of tickets, especially by the companions.