Networking will be around for a very, very long time. Even with wireless technology, WAN still will exist. I've studied wireless technology and was almost recruited by a wireless technology company. Routers, Switches, WANs, LANs, MAEs, NAPs, IXs...there is just too many key components in the whole "Networking" world for it to just all vanish. The technology will keep advancing and networking will just evolve to a higher level.
As for other computer-related fields...software engineering ALWAYS has job openings...UNIX has been around forever and is still big....there is always a need for system administrators.
BTW, I'm a network engineer...