We may never have 100% level 5 driving.

But with level 4 + remote assistance, you don't need to support all the edge cases to have a car with no steering wheel. You only need to reduce the need for remote assistance enough to make the economics work out.

We will all have been riding around happily in cars without steering wheels for decades before "true self driving" comes to pass.

It's possible that remote assistance centers will never shut down entirely, even 100 years from now, still waiting on the off-chance that a .00000000001% edge case pops up that the system still can't handle.