I think the way film making unions are organized is something to look into but my impression is that the problem space is more familiar when you look at what industrial worker unions deal with. That is: careers under a single employer instead of gigs where you go from employer to employer and have to basically get re-hired.

Hmm, but why shouldn't games work like a Hollywood-style gig economy, since the need for labor varies depending on a game's lifecycle?

The difference is that a lot of roles in film are individual. You can hire a director, a writer, a scenarist, a bunch of actors etc. separately and they will do their job just fine. And for the tasks, which require high-skill teamwork, movies contract a company, which employs the team full-time (e.g. VFX, stunts).

There are very few individual roles in games. Even leadership roles are highly dependant on their teams (just look at what happened to Visceral if you want an example). And there is a lot of interdisciplinary interaction too, so even if there were separate game programming, game design and game art houses, there is no guarantee their could work with each other in a productive manner. At best you can separate QA and some art teams, which already happens all the time.

that's true. I think something really unique in game dev is that parts of the team can fluctuate while another part has a larger commitment across several projects.

EDIT: I'll also add, although obvious to some but worth mentioning, that an effective game-dev union needs to help both those people equally.

I think its important to point out that there are a wide range of union constitutions & contracts - not all film jobs are gigs; there are contracts that cover workers who work for a single employer, like a tv studio, film projectionists, or arena stagehands (all IATSE)