You can find a job in that field, Here are some of the skills you will need.
1.-Linux know how to write scripts, bash. python, 2.-Learn to automate server setups with Chef,Puppet, Ansible 3.-Learn how to deploy software using Capistrano, Jenkins, Maven 4.-Learn how to help developers setup Dev Environments.
I am a sysadmin been doing this job for almost 12 years and I am not old but I not a spring chicken either, but I have job offers all the time. I have a great salary and I come home and learn more stuff everyday on my own. I get paid to do what I love.
It doesn't matter how old you are, if you are trying to compete with young developers that might be hard but I can tell you that developers hate setting up systems or debuging issues and that's where Devops engineers come in handy.
I have a few books i can send you if you are interested.
Cheers