I think Google Stadia may change its name to another name if there is a better name for Stadia, or Google buys another brand name or website domain name which sounds better.
I don't think they will change the name, to be honest. Firstly, it's a pretty good name. Google Stadia sounds nice and it's marketable so there aren't any issues there. Plus, changing the name is just going to cause too many issues that aren't worth it
Stadia may have another name in other countries if many people in other countries dont like the name, feel the name is not very memorable, and non-english speakers have problems pronouncing it.