I can't believe they actually did this. Maybe there really are only a handful left in v8.1(many of which are here in that case) so they bit the bullet. Will this affect how work is done in cars that are v9 and above? Can someone who knows Tesla's software elaborate on what this change actually does? Pros and cons etc?
It's not clear what you're asking, "Will this affect how work is done...".
Websocket is just a different (and far more efficient) way of acting on the RESTful API interface of the car, than the clunky and terrible OpenVPN. I've never bothered to learn OpenVPN and went to WireGuard exclusively, from IPSec.
The Tesla VPN was a direct point-to-point connexion with Tesla's servers, so services which used that are now completely on websocket, services such as firmware and map updates (which I never got and very much need), feedback to Tesla on roads, maps, app connectivity, etc.
Services such as mapping, traffic, streaming, etc are not done through the VPN but connect directly to the respective services. Supercharging on v1 Sc's should not be affected as this is a setting in the car. Assuming Sc was originally paid for in your car you can feel free to turn it back on if rooted; otherwise this would be unethical.
For those who are rooted I've been in the process of
overhauling and updating Lunar's scripts for security and functionality. Mine are practically unrecognizable from his now so can be considered a fork which I call 'solar', but MattG has my gratitude for blazing the trail. What my scripts will add up to is complete isolation from Tesla, first-ever backups of critical files from the CID to the IC and optionally to your home server, the addition of the advanced WireGuard VPN, and so on. I plan to also add 'nikola', which is MattG's phone app that I believe has functionality very much like Tesla's app, except it connects directly with your phone rather than through Tesla's servers.
These scripts are relevant to the newest firmware versions too, if taking countermeasures against new security measures. I don't have a newer car so can't advise... unless someone buys me one? :j