Yeah I mean it's literally what the term "open source rugpull" means. Every business will ultimately renege on their open source promises. It's literally against their fiduciary duty to shareholders not to, once they've run out of actual growth ideas. Even if current management is idealistic, eventually, they will be replaced with "real leaders" who know that they need to make money.

But, ideally, it's not that big a deal, because the community (or even newer non-calcified businesses) can fork the last open source branch and continue development.

Unfortunately, with something as complex as an OS, that's incredibly difficult. It does seem regrettably unlikely that, for the foreseeable future, there will be no practically usable open-source phone OSes.