28 nm can be good enough for a lot of things, and that's where open source could eventually become a viable option.

We will eventually reach a point where shrinking transistors provides diminishing returns, which should give open-source tooling and processes more time to close the gap. But we're probably still at least a decade away from seeing how that plays out, and who knows what happens with quantum computing, new materials, 3D integration, or some other semiconductor breakthrough in the meantime.

Even then, I don't think open source necessarily catches the absolute state of the art. Unless a startup fab decides to build its own EDA stack and open-source it as a way to attract customers, there will probably always be some gap between open and commercial tooling. The question is whether that gap eventually stops mattering for most designs