I think what we're really talking about here, if we wanted a copyright system that didn't allow corporations to own works, would be ending copyright assignment.
In that case, it's likely that part of your employment agreement would simply include a perpetual, exclusive, licensing agreement as well for all works performed on the job. It would be important that the company keep these licensing agreements on file, and would change the legal bias from "company presumed to own" to "company must demonstrate it owns," but that shouldn't really be that onerous. Companies already have to establish contractual basis for nearly everything they do anyways.
And it would put the cards on the table and it would probably make it easier (or at least more possible) to negotiate things like royalties on work that currently almost never gets it.
Also it'd make it a hell of a lot harder to exclude someone from the credits of a game because they quit 2 weeks before it went gold.
Exactly, creators would license their work to their employers and if not much much sooner, at least when the creators have died the copyright would expire and the company (along with everyone else) would be free to continue doing what they want with it.