Amir,
I think its safe to say that clearly. Microsoft is going to use Exchange 365, to force adoption of MS Office 365, by means of forcing adoption of MS Outlook 365, and that is it. You have made all previously solution break, you have made the previously current static desktop version 2019, timeout in 4 years (ending next year), and you are offering only a 4 year span on the newest Outlook Office Suite version 2021. The whole thing is a giant ripoff.
The answer is simply to drop Microsoft Exchange 365 support entirely. None of the so called options that you list make any financial sense to anyone, and that seems to be the Microsoft plan. Obviously, Microsoft doesn't want the small customers, unless they are on the monthly or annual subscription ripoff model, that is simply NOT a good value at all. And generally, there is nothing in Office 2021, or even Office 2019, 2016, 2013 that justifies ever buying them over 2010, or 2007, or even Office 2003. Feature after feature that was broken in 2003, is still broken in 2021. The new online Office versions are not worth SPIT. Try and actually use Web based MS Word to anything useful and productive. You simply cannot. Web based Excell, useless. Webbased Outlook deficient at best. Web based power point? MS OneDrive is the WORST PRODUCT I HAVE EVER USED IN MY LIFETIME. IT IS SO BAD, it will hold that record through the lifetimes of my grandchildren. OneNote, Project, Teams are so vastly inferior and problem plagued, I don't understand why anyone would buy them. (Just today I HAD to use teams for a meeting. I have teams, the current version, it would not work.... The browser based Teams would not work, Only the download from the network (10 minute load) finally worked, making me 15 minutes late.
Microsoft just keeps asking more and more and more money, for worse and worse and worse solutions. You found my line. I'm done. A terrible company that does not care about the quality of its product offering in any manner means or method. TERRIBLE.