I don't see the real problem here. By its nature, FOSS software cannot be monopolized. If party A decides to replace a legit license with one of these commercial source-available licenses, just fork the last commit using the original license and develop from there.
Oh but wait -- the community, the contributors, the users are all attached to the original project. Well, that's competition: make your version better, advertise the licensing issue; poach the original community.
Oh but wait -- the community, the contributors, the users are all attached to the original project. Well, that's competition: make your version better, advertise the licensing issue; poach the original community.
Case in point: