Companies try to keep users locked into their ecosystem but the companies come and go!
It's a pain, and I now wish we just have internet connected hard drives where we can save whatever we want.
That’s how it should be. You have your data under your control and give companies access which you then can revoke whenever you wish.
When I joined Strava (8 years ago... wow time moves fast) I immediately realized it's not the best place to use as main storage of your fitness activities. Not just because it might just "go away" at any time (and back then they didn't have any clear monetization plan, not that it's much better now) but because it didn't seem to provide a mechanism to bulk upload/download the original .fit files. You uploaded a .fit file but then downloaded some other format (.gpx I believe?). That made it clear it's not a good place for archiving/storage. Since .fit files are really small, even using something like Google Drive's 5GB free tier should be plenty for many years of fitness activity storage.
At least... not without sharing the data even wider to jump from sync service to sync service until a magical path or co-operation emerges that connects the two services together!
I still recommend Tapiriik, it can sync between a lot of different services. I don't like the idea of having years worth of personal data on a proprietary platform, so I like the ability to keep them as GPX-files on Dropbox.
Even if they don't go anywhere, all it takes is to not support certain devices, block some other services, maybe focus on a different market (They didn't use to be as into fitness trackers), etc.