> So it will be illegal to use Whisper systems Signal?
No. If Whisper systems didn't comply, they'd be blocked.
> Is there any mechanism for Germany to influence corporations outside of Germany?
Well, if they're in a EU country, there are plenty. For non-EU: not so much.
Seehofer is known to make outlandish proposals, however. It's likely just a way to start the debate and position himself/his party as "tough on crime" before tomorrow's EU election in Germany. I don't believe that it will happen anywhere close to this, since Germany isn't a market so large you can't ignore it. Messengers will simply say "oh well", be blocked in Germany and Germans will be unhappy.
