I've been thinking exactly along these lines myself. I bet a lot of people are thinking that self-driving + electric will bring van life to a whole new level. It may become the reality that a large number of people actually, purposefully, live in self driving vehicles/homes since removing the 'car' part greatly improves the living part.

I’ve wanted a lay-flat ride between San Francisco and the South Bay for ages.

Crash safety and the need for seatbelts will limit what can be done with the interior. There won't be any lay-flat seating.

> won't be any lay-flat seating

If crash rates go down, and you have a flat surface that you’re strapped onto that is angled and has an airbag-like system to ensure as many G’s as eyeballs in or out, sure we could.

As far as my imagination goes any efficient seatbelts for a person lying down will be very painful in even a small incident if the passenger has a scrotum.

You can check out the Hyundai Ioniq 7 for an idea of a non-conventional interior. Even then it still needs a driver's seat for the current day, so it can radicalize even further.

Though I'm not sure if we'll ever fully get to such a state. I can see driver's seats still being mandated in case of failure and a need to revert to manual driving.