If you think that the
Geary + GNOME Contacts + GNOME Calendar + GNOME Tasks can handle the
enterprise usage, then it's great.
Actually they don't because online accounts doesn't yet have CalDav or
CardDav support. Don't think just for gmail users. So the only way I can
have all these into Gnome is through Evolution. I don't use it as a
client because of UI issues. But Geary & California or even Gnome
Calendar & Gnome Contacts sync with evolution-data-server for these kind
of data.
So until Online Accounts gets up to speed with Open Standards, I think
it would be a step back (in terms of Workstation functionality) to drop
Evolution.
~nikos