1 year? Jesus christ. You know, in other industries things are routinely supported for decades. It is a good thing large chunks of actually essential infrastructure aren't designed by web people.
Once a feature has been out on all major browsers for a year than its fair game to use. Its also not wasting your time trying to develop a modern web app which has support for netscape navigator.
Going off the usage stats of the site I work on, almost everyone is on the latest version of their browser and the ones that are not always end up upgrading after a warning notice is sent out about old borwsers.