All current plans have a transition provision so preexisting conditions will be covered.
The "age tax" you speak of is an obvious necessity, as we age we use more healthcare. If you'r talking about insurance there is no point, if you are talking about socialized medicine you are just placing your burden on someone else which is what socialism is all about. Stealing from one person to give to another  while making the politician rich. 2 wolves and a lamb deciding on diner....