Everyone in the US has committed to NACS in the next couple years. The others are aware of this and if they are not completely stupid making plans. They will probably support CCS for a while in some form, but they will be doing NACS in the near future. It might be like regular/premium/diesel fuels - pumps support more than one hose (though wire is more expensive than a hose).
Tesla version 3 superchargers already use CCS for communication between car and charger for 2019 and later vehicles.
Version 2 superchargers do not speak CCS and won't ever be opened to non-Tesla vehicles and there are certain routes where that's quite annoying. My most common road trip has 5 supercharger locations along the way with 3 of them being V2, including the most isolated charger. Even once the NACS changeover happens taking a non-tesla on that journey will be a real pain.
Tesla has not put any resources into converting V2 sites into V3s. Some of the locations have been expanded with the new additions being V3, but I haven't seen much in the way of switchover.
Now that it's open and standardized, you'll probably see tons of third party charging stations with the NACS plug. Tesla's part in bootstrapping charging infra to make EVs viable seems to be mostly done.
No compatibility break as far as I know. I believe V3 superchargers speak CCS to 2019 and newer cars and fallback to the older Tesla-proprietary communication if necessary.