The marvelous technology of recording a voice, that's been around for a fairly long time. This issue is being overly complicated when it's simple. Just have someone voice the announcements so it's more human. It isn't difficult. That they're replacing it without word (on my end) that he wants to step down is a different but related topic.

The semantics of futureproof are very important. "Semantics" isn't a cliché to wave away a topic.

>A new T line in 2022 can use the same voice as the current ones and also potential new developments in 2040.

Why are you invested in this so strongly? This is very odd. It's like you're anxious about solving a problem that doesn't need solving.

>benefits of improvements.

This is a benefit to some bottom line, not a benefit to the service. And having someone do the voices isn't that big a deal. I'm certainly skeptical of technology is a healthy way; it has to prove useful. In this case, it proves useful to management, not designers. Or anyone, really. I have a feeling you jump way too quickly into the idea that any technological improvement is some universal good.