The real question is, would we consider MongoDB or my former employer, HashiCorp's products, presently open source projects?

In the latter's case, the answer from the community at large has been to fork (edit: not always successfully), giving a fairly good indication as to the answer...

(Whether this is as a result of the act of relicensing the code base or as a result of the license choice probably cannot be fully understood without parallel universes... I'm sure someone would complain and potentially fork if they had relicensed, e.g., from MPLv2 to AGPLv3--another OSI license, but a more restrictive one--though probably nobody would care enough to fork if they had suggested e.g., MIT instead, because the MIT is more permissive.)

However, developer categorization into OSI/non-OSI buckets is rather meaningless.

What we've by and large found is that Linux businesses (regardless of license model, even fully proprietary) can usually find funding, due to the large number of companies willing to pay for support & contract development on it. Many more businesses have been successful here: vendors like RH, Canonical, SUSE, Oracle, and even Microsoft and AWS, but also many smaller vendors & independent developers who make smaller livings and profits.

What's been harder has been the non-Linux Open Source/Free Software business model.

And that's what needs to be solved, one way or another. Perhaps that's committing up front to a license (if you want to use the BUSL, so be it, but don't expect the community to be happy if you do so after your project becomes successful).

But more likely, its by raising awareness and making sure people at the top of the organization (board members, shareholders) understand the value of OSI licenses and how their companies can benefit from it. And on the flip side, how changing the terms of contracts afterwards can cause problems. :-)

I think what OP is talking about is change in the (for rebuilders) source distribution availability, e.g., https://www.redhat.com/en/blog/furthering-evolution-centos-s... -- but as a later blog post points out (https://www.redhat.com/en/blog/red-hats-commitment-open-sour...), the source is still available in a different location, though perhaps at a slightly different point in the release cycle: forward looking to RHEL next.

My response is in that context, that even if one were to consider the removal of those source locations somehow a "license change" (and I agree with you, it is not), nearly everyone working on RHEL would still be an OSI developer, for reasons pointed out by Mike.

Which is a very good thing, and as a former Red Hatter, thank you for helping to keep that possible Richard!