I'm not sure if you understand what I'm saying, it's just moving the ots proof and creating an additional layer of abstraction so that uX would be better imo. right now I believe your proposal means if someone gets compromised they have a minimum of x amount of time before you could migrate. 

The suggestion I'm saying is to bake that in ahead of time and make migration fast if compromised.

also in the case your new key were to get compromised before migraine, this would help with that, since you aren't pegged to a specific new keypair