[erichocean]

If it's in public domain, all of them will use it, then make separate forks, and maintain them (individually, or in groups).

SQLite is almost exactly analogous to what you described (database, public domain).

AFAIK, there is no widely-used SQLite fork.

IOW, the situation you describe with every company "maintaining their own fork" literally did not happen to the software that's the closest case study in real life to what you describe.