How would that even work? Apps distributed outside the App Store would not (necessarily) be submitted to Apple to review, and the developer of sideloaded apps may not be identifiable to charge fees too.

I suppose they could mandate some sort of signing system for sideloaded executables but I have a feeling the EU would consider that a further abuse.

It will all come out in the wash, but if the rumours are true Apple seems to be going about this in the worst way possible.