I'm currenty working on industrial control system for Ukrainian power plants, railway stations etc. We provide 30 years of mantainance for our system so, while moving our current release to the newest kernel possible, we are still stuck with things like Fedora 12, Linux kernel 2.6 or GCC 4.4. And this is way far from our oldest technology stack, it's just what I personally work with.
Please don't tell me to upgrade. I appreciate your concern, but my job is my job.