Automatically roll worlds after 60 days (and only after 60 days) after roll over with simmy running the open teams. The "good" worlds will still fill with all humans, while allowing the others to play - the 60 day wait would still incentivize commissioners to recruit, but would alleviate the glut of worlds sitting idle.
Alternatively, a policy could be put in place that worlds sitting for 60 days are closed or merged until supply of worlds matches demand. This could alienate some owners who lose their teams/world history, but may incentivize other owners in the world to pitch in and help recruit or at least be active in promoting their world or risk losing their teams.
A system where there is a massive number of leagues sitting idle with a huge number of openings for long periods of time is clearly broken, and not how the game was intended to function (at least I hope not). A system where a single paying customer (commissioner) is solely relied on (in many cases) to attract other customers to the product is a poor strategy. Yes, there is a handful of commissioners that go above and beyond and successfully complete quick rollovers. But there aren't 141 of those (or however many worlds there are) and even commissioners who put in a fair amount of effort run into brick walls when there are a massive amount of openings overall and few owners willing to take on new teams, unless there is some recruiting secret I am missing, in which case please sitemail me with what that is.
All in all, I don't expect much to change, as there aren't adequate support resources dedicated by SportsHub to address such issues.