> you're doomed

You're making a big stretch here. Sure, you can be left in the dust behind their proprietary fork, that's true: https://hypercritical.co/2013/04/12/code-hard-or-go-home

But your habitual workflow isn't "doomed". You can always fork and keep using the same open version of the project that you've always used. If the project is popular enough, there's usually a community that keeps maintaining that fork.

That's the deal that you get. Free software was never about "free upgrades forever". It's about the freedom to fork.