If you want to have provider choice for customers and interoperability between messaging apps, I don't think there is another way than making standards mandatory.
Why do you think WhatsApp reached a billion dollar evaluation? Not because users have the freedom to move to a different provider and still be able to talk to all their friends...
The only other possibility is that users start rejecting providers who do not comply with internet standards (and I don't see that happening, even here on Hacker News).
Making something mandatory will definitely push things forward because what else are the providers going to do? Though I still have doubts about real progress being made. EU can't can even add VP9 and AV1 to the list of codecs used for Digital Video Broadcasting (DVB).
Instead maybe the government should start eating its own dog food and use an open standard for both internal and external use.
Why do you think WhatsApp reached a billion dollar evaluation? Not because users have the freedom to move to a different provider and still be able to talk to all their friends...
The only other possibility is that users start rejecting providers who do not comply with internet standards (and I don't see that happening, even here on Hacker News).