Comment There is already a solution (Score 2, Insightful) 180
Developers can stop using flash and end-users should uninstall it. There is already a solution out there and it is called javascript. 90% of the things you can do in flash can easily be done using javascript, jquery, or some other javascript framework. For the remaining 10%, HTML 5 will be able to handle most of it (canvas tag, videos, better form support, etc), and the remainder of things that javascript/html can't do that flash can do (if there is anything), is not even worth implementing in a website.
Since javascript and HTML is all open and much easier to work with, I foresee flash and silverlight on the decline. This especially holds true when HTML 5 is fully supported in most people's browsers.