I apologize for coming in late but I've been offline longer than usual. At forty-six I receive at least five phone calls a day and anywhere from six to ten emails every day asking if I am available for work. To be fair I only do contract work and usually only take three to six months contracts, so I must agree that a person over thirty will likely never get a full time position at any company unless they are willing to work for much less than they deserve.
That being said, I can only offer the following advice in remaining in demand as a software engineer even into your forties and beyond. I'm being brutal for a reason so unless you have a clear rebuttal don't reply..
1) And this sucks. If you haven't been programming almost your entire life, twelve, thirteen possibly as late as sixteen, you don't have a chance.
2) You have nothing to do with open source, shareware, kumbaya software, game programming.
3) Don't even try to be a jack of all trades, pick a poison and stick with it.
___a) Case in point. I bit the bullet at Sprint circa 2002 and focused exclusively on .Net, which at the time was not even close to being a sure thing.
___b) I hated C the first time I saw it in the fall of 1987 but was smart enough to realize that C# was the future if you wanted to develop MS software.
4) This is probably the worse part of staying relevant after 40. While I love my wife and children, I don't have any hobbies, I don't go to movies, I don't read fiction. What I do is read Slashdot, shameless plug, and make sure that I am one of the first people anywhere on this planet that masters any new technology coming down the pike.
5) HTML5, HTML5, HTML5, HTML5 and in the MS world MVC3 / Razor.
6) 51Degrees, 51Degrees. If you are over forty and don't know what that is your getting very close to being too late.
You do realize if I was paid the same amount of money I am making know, I would go back to building mansions in the Hamptons.