Real progress would be something that can force Moxie Marlinspike, who lives in the US, to introduce a backdoor.

They can't easily shut the service down without risking a lot of unwanted public attention. When "why can't I message grandma" is answered with "here's the list of politicians that caused that because they want to spy on your messages", those politicians will have a bad time. I think Signal is popular enough in Europe to be protected by this.