Still that won't help if the company you are working for goes out of business.
Other things.
5) Don't burn bridges: try to avoid making enemies. A bad reputation can hurt. Rumors, can spread. That guy who you hated and never gotten along with, may be the same guy who you will need to give you a decent review.
6) Know your industry: Chances are most Technology professionals are not in the technology industry. We can be in Healthcare, Manufacturing, Retail, Government, NGO, Finance... A pop in the tech bubble doesn't mean your job will pop. If you have a good foot hold in one particular industry, use that to your advantage. Sure due to the collapse you can get cheap programmers, but do they know the industry as well as you do.
7) Industry diversification: Try to have a fall back industry you can go back on. The thing about economic bubbles is they don't know the difference between a bubble and a strong growth sector until it pops. Know how to translate your skill to other industries, try to keep up with what other industries are doing.
8) Keep an eye on your companies culture. Especially in smaller organizations changes in your bosses behavior is a good sign that something is up. Normally these guys are A+ Personalities who love to talk, then you find them being quite and reserved. You find that they are pushing harder then normal, for unknown reasons. Or finding ways to save money that seems to be more nitpicking.... That may be a good sign to polish your resume and start interviewing. Even if you don't think you will be targeted, because you are the star worker. Being the last one standing after layoffs really suck.
9) Don't be in the same position and don't be a job hopper. You normally should be getting some sort of promotion (either in title or by compensation greater then normal companies salary adjustments) within every 3-6 years. Anything less then that, a company will be afraid to invest in you. Too much more Then it looks like you are happy with a dead end job. You can work at the same company for many years longer... But you will need to show growth in the career, promotions are one way. Or at least you can explain the change in your work, more then just changing technology.
10) Avoid being a hater: Keep your anti-windows or your how ethically wrong closed source to yourself, or at least professionally, even if you are working in a position where you are using Linux and making Open source tools. By hating something, you have closed your life off from a different path. Some people will negatively call it being a a sell out, But you really should keep in mind how fixed and important your beliefs are. We care for a lot of things... However we don't care about all things equally. Say your work does a lot of good, however you need to use Windows... Does the face the Operating System that you are using that you dislike is equally or greater in its badness that it counteracts all the good that your job does?