I am unemployable because I'm a white male whose in his 40s, has a family, and because somehow, in this industry experience is a bad thing.
It amazes me how intolerant of age and differing opinion tech culture is.
The key to keeping yourself relevant is understanding the big picture, and learning stuff that is outside your area of expertise. For example, I started as a network engineer, but got into UNIX because I wanted to know how the provisioning systems worked that ran on Sun boxes. Then I moved into UNIX sysadmin work, and I found that I could run circles around most sysadmins because I understood how the network functioned and could troubleshoot beyond a single box (hint: it's (almost) always a DNS problem... :) After you've stood up a few complete datacenters or soup to nuts web infrastructure for a few medium sized companies, you move into architecture, but you need to keep yourself relevant and current. Here is a rough timeline of what I was focused on:
1990-1994 - Novell Netware, WordPerfect Office (became Novell Groupwise) 1994-1999 - Network engineering at an ISP, got into UNIX. 1999-2005 - Solaris system administration (2001-2002 was rough and was out of work for about 9 months during the dot com crash) 2005-2008 - Linux system administration - got into storage administration and became a SAN/storage architect. Started going really deep on configuration management, CFengine, later Chef/Puppet - automate all the things! 2009-2013 - VMware and private cloud - my skills as a storage architect led me to a natural role as a VMware architect, and automated provisioning infrastructure as a service. 2013-now - public cloud/AWS.
Keep reinventing yourself, and you have to really enjoy learning new things, or you won't last long in this industry. I think that's probably true of any job, though, honestly. Would you want to see a doctor that hadn't learned anything since he left medical school? I sure wouldn't...