@shanecelis I think I explained myself poorly here.

If your hypothetical grid supports 1 TW with constant demand, of which 50% is renewable, then the desire to eradicate the 50% non-renewable is low. The up-front cost of building infra is high, maybe too high to leave the local minimum status quo.

But if you've projected demand for 2 TW next year, it's time to get building for an extra TW: and while you're at it, why not the extra capacity needed to ditch the 0.5 TW of non-renewable power too?