[AstralStorm]

Technically, you could deliver revocations via a carrier pigeon, but of course it opens a joke hole of an attack. Unless it's a short distance for the pigeons.

As does automatic unvetted certificate signing (because non-repudiation), or automatic instant revocation process. (Denial of service or downgrade)

Pick your poison.

[cryptonector]

People get bit by certificate expiration all the time.

The only way to make sure you don't get bitten by things like certificate expiration is to exercise update path often, and the more often the better.