The next step would be to make features like "read receipts" that necessitate signing into a cloud optional. Being able to use the app without having to sign into a cloud platform would be a much more valuable feature for me than any feature such a cloud platform could enable.
Aside: as mentioned elsewhere in the thread, tracking pixel based read receipts in particular, is overwhelmingly only used in spam and newsletters and I personally consider it to be a liability rather than a feature.