I don't think anyone is saying immediately, but these are long-lived fairly static systems. I'm going to assume that you probably update your server's SSHd at

I don't think anyone is saying immediately, but these are long-lived fairly static systems. I'm going to assume that you probably update your server's SSHd at least semi-regularly and that if SSH turns out to be broken 20 years down the line, you will probably be switching to something better either manually or when you eventually replace your hardware and reinstall the OS. This kind of infrastructure is meant to last for decades. Imagine if the original GSM contained a backdoor with the state-of-the-art crypto of the time. Would it still hold up today? Hell, you don't have to imagine - a mid-range smartphone these days can crack a lot of GSM traffic. Besides that, there's also the problem that not only are these things usually not done with state-of-the-art tech, but leaks happen all the time and it only takes one mistake* for the privkeys to become known.