Isn't this the same problem that music has though? The vast majority of musicians don't make a huge living from creating their own music. You either do it for the joy of it with the hope of possibly being discovered. Struggling artist etc. With the main difference being that software developers skills are also hugely wanted in other markets, which musician skills normally aren't.

On some level, its a question of how you both eat the cookie and have it, right? What independent game developers want is some guarantee of a base income, but also with the option to cash in big if they do make it big.

Maybe there is an opportunity there - I'm not sure if a credits organisation is what you're looking for. But maybe something like a self-organised fund that will buy stakes in individual projects, where the stakes are paid out more in a salary style?

Semi-organised group of indie-game developers that guarantee a (lowish) living income to all in the group in exchange for a relatively large chunk of any large windfalls to support the future. If games are actually sustainable then something like that feels like it could stand a reasonable chance, right? Assuming you get past a critical size and have some name recognition. Could also move into the same benefit areas that unions do.

Essentially something like your own very light-weight union/co-op.