[rjvir]

I think it's plausible that they'd offer E2EE for all of iCloud.

They already do it for iMessage, and it makes it easier to turn down subpoenas if they can credibly claim that they can't even access the data themselves.

Likewise, offering an explicit choice also seems plausible. The full E2EE flow might have UX downsides (for example, the user might need to write down a recovery seed phrase on paper), so they might not force all users into that flow.

[cwizou]

But that's the thing, they have reached a compromise regarding iMessage being "E2EE" by keeping all those avenues (iCloud backups and iMessage on iCloud) that essentially trade E2EE for the convenience.

Most users opt-in to the convenience for iMessage making it, for all purposes, no longer E2EE.

I don't see them removing that precisely because of iMessage.