The encryption itself will work "forever." (Realistically, very powerful computers could some day obviate contemporary encryption). The tricky part about PKI a

The encryption itself will work "forever." (Realistically, very powerful computers could some day obviate contemporary encryption). The tricky part about PKI and signed TLS certificates has little to do with the encryption and a lot to do with networks of trusted parties. People die and are born, relationships evolve, and so these networks are inherently dynamic. Certificate expiration is a feature by design, and it's included for a reason.