Yes, the bearing can be replaced. See the 1400 bearing thread thats up right now.
In my experience, the heavy duty Eureka motors have very long lasting bearings. Ive serviced Sanitaire machines that have seen heavy daily use and their bearings sound smooth as silk.
Seems most techs would replace the entire lower motor housing rather than go thru the trouble of drilling rivets.
Unless the bearings were ruined somehow, I think its very reasonable to just leave them be. Youd sooner wear out the belt pulley or the carbons before wearing out the bearings.
The carbons in the Eureka pancake motors last a LOOONG time as well.