Hackers are like germs.  You throw equivalents of antibiotics at them, they'll mutate into superbugs.  For example, I doubt phishers will be tempted to hack Google to take advantage of AdSense Voluntary XSS vulnerability because they are getting enough loot from stupid phishing attacks to keep them happy.  Once Microsoft Outlook, the main phishing delivery vehicle, is plugged and their gravytrain runs out, they will turn into superbugs to find other means of getting their phishing lures in front of the user's eyeballs.

Oops.  I am out of tea for now.