Hybrid Pubic Folders :
You would have to move the
Public Folders to EXO before
decommissioning Exchange.
Ability to Offboard:
Having Exchange on-premises is
the only way you can offboard a
mailbox. If you remove
Exchange, that capability would
be gone
SMTP relay:
Email from an app or device
(such as a printer); can transition
this directly to EOP, but a relay
server on-premises is often
recommended
