Threema will be forced to stop serving EU customers via IP scan for example and the app stores will ban it. Normies will have to adapt quickly.
The EU is not able to force Threema to anything! There is no legal way for that!
"What is crystal clear, however, is that there will never be a Threema version that’s spying on its users in any way, shape, or form. The reason Threema was created is to provide a highly secure, completely private, and anonymous means of communication. " https://threema.ch/en/blog/posts/stop-chat-control
You think a company can break EU law without consequences?
"What is crystal clear, however, is that there will never be a Threema version that’s spying on its users in any way, shape, or form. The reason Threema was created is to provide a highly secure, completely private, and anonymous means of communication." Threema
Sure, and I hope that's the case. Nevertheless, it remains the case that the company cannot offer its services with impunity in the EU after the law has been passed.