This is where we get to the double edged sword, let's say all keys had a mandatory "upgrade" this would mean that essentially every person "against their will" would be forced to make a new key pair, or at least their wallet code would be forced to make a new key pair. To create a new secured key is also going to have to require the key to be assigned into the blockchain with a balance that is associated with its previous key which would require the owner to make the signature creating a swarm of transactions and a big mess.

It also puts code into the core that essentially breaks any choice or privacy if your keys just randomly assign themselves to another key and make a transaction without you having any say in it. In my opinion, the best thing for Bitcoin now would be variety of keys available for choice so that people can slowly start the transition now rather than waiting until the eleventh hour.

Thank You,
Viz.