Neil Jordan I believe that the number of people being able to maintain VBA and develop it getting smaller. Same with W/Cscript. The security constraints doesn't make it easier.
I agree with you that have been predicted for a long time, same with plugins that should be all migrated to Office Store Apps.
A clearer roadmap when Outlook legacy (win32) App will be replaced by the Web pendant would be very feasible, not only for Windows 10/11 Mail and Calendar.
Repeating myself Outlook legacy uses many old techs, where we have to believe that even Microsoft will have a hard time to find developers to understand and maintain the code and security of Outlook / MSMAPI and the ties in Windows OS reaching back to Windows NT.
I don't believe this move is made to appear modern, because web apps are the lastest and greatest, rather a necessary step to compensate loss of knowledge at Microsoft for old technology due to retirements etc, considering the age of Outlook and Windows.
We are seeing similar developments in other areas, e. g. Windows Server Features that have become a frozen zone or are on the list of deprecation. After all mmc consoles and RSAT Tools in 2016, popular wmic is one of the lastest additions.
I believe MS Access will be around for quite some time. The Access Runtime barely receives updates since 2016.
Could be a forseeable time we will be loosing the advanced integration between Office products you mentioned, if they are not ported or refactored to plugins based on Office Store. Just my two cents.
Clarity is necessary for users, admins and developers. We had the same unclear agenda about M365 end of support on Windows Server, two times now. This shouldn't be repeated about the lifetime of the Outlook legacy app.