I feel that's pretty disingenuous. Like you noticed the server-side code is active, and changing server address would be a niche-of-a-niche activity. Also, what would be the point of going after Signal's servers? Even if a/the government got a hold of all the data in there, it's encrypted with client keys. I mean sure, if they took over secretly and became a malicious MITM that's different, but it's still only for any future messages, not history. Not to mention I'd be inclined to believe they'd get the word out.

Signal's research and protocol is already used in, well, basically each and every discussion/video platform. WhatsApp, Telegram, Skype, Facebook Messenger, Google Messages, Duo... so it's hard to see Signal becoming more ubiquitous. Seeing the app more will probably happen naturally when events happen (like the WhatsApp privacy change) to drive people towards more secure platforms, but honestly I don't really see a major shift anytime soon.