Chat Control hasn't happened, and if it does, the court will shut it down. (It's still worth fighting, but it's not something that non-activists need to worry about.)
One can't rely on courts only to protect civil freedoms. If and when totalitarian measures become politically acceptable and desired, the politicians will simply amend the EU treaties and national constitutions to allow mass surveillance, and disband or subvert CoE and other limitations to their power.
