That is, incompatible with other e-mail clients and servers and Internet protocols. So both are slated for migration to Exchange. The chief incompatibility is long file name support. Then there is the hardware. 128 megabytes of RAM and 4 gigabytes of disk space just doesn't cut it for a main server anymore.
Software is too large and there are more and more users using the network more and more.
Columbia faces a gradual phase out that already started this fall. No new students will be added to the Netware network servers. Student e-mail will be handed off to Pluto. Columbia will probably be powered down and ultimately used for something else. Apollo and Enterprise have secondary roles as routers and may continue in those roles for a while after that since routing is relatively unaffected by the date bug.