With a little knowledge, it's not very hard to make your own messaging app and share it with those you know. And there's plenty projects online that give you what you need without having to write the code yourself. Alternatively, there's just plenty dark web and under the radar apps already that won't bend to this ruling.
What it is, though, is very inconvenient and annoying to do so.
But if you're an actual criminal, then there is this solution here that can never be subject to this ruling.
So what this clearly means is that the EU will violate the privacy of all the everyday people that don't handle that inconvenience, pushing the serious criminals to dark channels.