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.
I've often wondered how well a restaurant would do in areas where those platforms are popular if it just dropped its customer-facing storefront entirely and went entirely online delivery.
The drop in operating costs versus the lack of walk-ins ...