I've started seeing this in the bay area. There are definitely places in SF which are lunch-catering only (via ZeroCater/Zesty) with no retail presence. Also there's a pizza delivery company in the East Bay (pizzamatador.com) which has no phone number, no store front (shopify website only) and will deliver you a par-baked pizza in <20mins. SpoonRocket (R.I.P.) was also delivery via app and their kitchens were in West Berkeley instead of a more expensive location that allowed foot traffic.

I expect you'll see more non-traditional kitchen locations and alternative delivery transport methods (e.g. scooters or Postmates bike couriers) to combat the high rents, congestion and parking issues common to most dense cities.