"Relying on tech"
https://www.theverge.com/2021/11/23/22798880/polestar-5-precept-electric-sedan-tease-2024
The "production-ready concept" of the Polestar 5 "Precept" looks like it keeping the concept's lack of a rear window. They can just use cameras to accomplish the same thing.
We are probably 10~15 years away from Mercedes or Bentley releasing a model without any external glass. Metal would better insulate the interior, making it quieter and safer, and they can just put screens on the inside to project whatever the passengers want to see.
Stuff like that will eventually trickle down to the mass market, presuming it works well enough. So maybe 25 years from now?