Your tutor is talking rubbish (imho).
Network staff are highly employable, especially the way Cisco (and others) are moving into appliances, turning their switches into multi-purpose devices.
And, if cloud computing takes off, more and more companies and people will be keeping their applications off-site, so reducing the need for MS staff, but they still need to be connected (by a network....
).
If you want my advice, go down the Cisco route (but learn about MS servers etc as well, as breadth is important, as well as depth).