The only "big studio" I pay any attention to is Nintendo, because they make games like a midsize to indie firm: Fun gameplay
Otherwise, I think all of the things a "big studio" does now, primarily the backend for online and p2p services is going to have it's open source / platform killer app soon. Valve almost did it with HL/Garry's Mod/ etc but they've stalled out recently.
Whomever develops a truly plug and play infrastructure module, handling networking, server config, deployment, etc will own a big boat by 2029.
As will the guy who figures out distributed PnP microtransactions.
AI and ML will likely be capable of full service character design and modeling in the next 5 years.
So things will change, and democratize like almost all of the rest of tech has as things become less human capital intensive.