Field service engineering jobs should increase as technology becomes more advanced. I'll give you my example.
I have an interview with a company that makes automated specimen processing units. Before these machines came out lab techs would have to do some tedious and repetitive work wasting staff resources. So this new machine replaces the many hours that would be wasted doing such tasks. While you eliminated a few jobs with the machine, you also added a new job because they need a person to maintain the machine. That's where Field Service Engineers come in. This trend should continue as long technology keeps improving.
The best places to look for these kind of jobs are in cities that have major airports like Atlanta, Dallas, Chicago, ect. Since traveling will be a big part of the job.