Any source on that “they plan on removing end-to-end encryption” other than uneducated speculation?
To some extent the announcement of him leaving, following changes to terms of service last year, make if for a very good canary in the coal mine kind of warning, that even if bound by confidentiality or other agreements preventing disclosure, he's leaving $4B behind for "some reason". I'm sure if it was to launch a new venture that'd be fine to disclose...