I regularly use my old Canon 30D...which is about six years old now? My 5D was bought used and I can't imagine "updating" it to a newer model. If anything, I'll buy another 5D.
(I still have my old Olympus E-10 and a Canon 10D, but only the 10D gets any use and that is rare. It just isn't worth anything, so it isn't worth selling.)