@OP. So, if you're the only person left in your department with your skill set performing your job function, you take it easy. In my team, there are a couple of my coworkers plus myself in the same situation, since our "backup" positions went out of the door last year with the layoffs.
If you believe your skill set is very important to the company, you could breath easy knowing you'd be spared from future layoffs. Personally, I still believe I'm fair game for layoffs, even as my work is directly related to the plants, since managers don't have a clue about technical matters, and maybe they truly believe that any employee can be replaced by other with no repercussion in quality, like it happens at the plants or to the LLs themselves. Managers don't realize that both, plant and management, are uneducated workforces.
If you don't feel safe and have no pension, like I do, then the path is clear. Polish your resume, get up to date with the latest technical trends, start interviewing for the next job, while you do ONLY your 40 hours. After all, we live in a world dominated by markets, and if the company truly has demand of your skills, and your skill set is unique in the company (low supply), then you dictate the terms of engagement.