When the Heartbleed vulnerability was announced, we found 600k systems vulnerable. A month later, we found that half had been patched, and only 300k were vulnerable. Last night, now slightly over two months after Heartbleed, we scanned again, and found 300k (309,197) still vulnerable. This is done by simply scanning on port 443, I haven't check other ports.
This indicates people have stopped even trying to patch. We should see a slow decrease over the next decade as older systems are slowly replaced. Even a decade from now, though, I still expect to find thousands of systems, including critical ones, still vulnerable. I'll scan again next month, then at the 6 month mark, and then yearly after that to track the progress.
NOTE FROM CLEMENT: Such is reality today, I guess we have job security for a long time to come