Apple has not announced anything about E2EE, you are right, that is speculative. I think this intention is telegraphed by a few recent actions they’ve taken, from strongest to weakest evidence:
1. The fact that they built device-side scanning in the first place when they could have done it quietly on the server. They invested significant engineering time into the advanced cryptographic algorithms used, such as the private set intersection and threshold secret sharing. They had their work vetted, in public, by well-known cryptographers from academia. This is all leading-edge cryptographic engineering, most of which I would bet is being deployed in a consumer product for the first time ever.
It only makes sense that they would do this if they intend to cut off the capability for this type of scanning on the server altogether.
2. They recently added more account recovery options, a necessary step towards helping the average user avoid catastrophic loss of E2EE data if they need to reset their password.
3. They announced well outside of their regular cycle of product announcements (June, September). This is unusual for Apple and could mean they plan to announce something else like E2EE in September. In their public statements they have indicated that this is one component of future unspecified plans.
iMessage, FaceTime, iCloud Keychain, etc. are all E2EE. It is not completely unreasonable to think that they would endeavor to encrypt more content. If there were political hurdles to doing so in the past (as reported), these might be mitigated by the new features.