using BSD/MIT licences is like betting against black swan event
sure, "contributing is cheaper than maintaining a fork" is true most of the time - but the moment new Microsoft comes in with "embrace, extend, extinguish" (or just copy and change), you're doomed
and heck, we had that exact thing happen last autumn, iirc - making big news on this website
Can you clarify what happened last autumn? I'm not sure I recall.
> 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.