Musk said a few days ago Tesla is going to open up super charger stations to other EVs, we'll see what happens.
Yeah, that's gonna take some work. Super Chargers are situated around the charge port being driver side rear, no input devices (screens, card readers, etc.) Companies are going to have to pay and make their cars compatible.
The only other company that currently matches the Tesla network is Aptera, and that's a niche car. Maybe they could make a Tesla-to-CCS device, other-car-owners could get a Tesla account, and VW (or whoever) could update it's software.