Now how the hell do we create a webserver that will work reliably for the next 30 years if we have to embed SSL certificates with built-in expiration dates in the range of 1 to 3 years?

You can use self-signed certificates. Your clients will have to trust them (by updating their stores). That's hardly an ideal solution (deployment and security wise).

More broadly speaking, you can't rely on anything to stay the same in 30 years, in terms of infrastructure. Many companies therefore deliver both the devices themselves, as-well as the systems to control them (ie. custom laptops/tablets). More costly for everyone involved.