I am aware of the limitations, but covering some predefined area with no human intervention is the definition of L4. Clearly there is non-zero development risk

I am aware of the limitations, but covering some predefined area with no human intervention is the definition of L4. Clearly there is non-zero development risk here, but I don't think it's going so badly that it's definitely going to take 10+ years to launch in a metro area with millions of people. It may take a decade to get to a coast-to-coast system, but there's not a whole lot of incentive to build that vs serving a few large metros in the near future.