Chrome and Firefox aren't interested in selling OS upgrades, which means they're not going to cannibalize their own sales. If we look at the closest comparison

Chrome and Firefox aren't interested in selling OS upgrades, which means they're not going to cannibalize their own sales. If we look at the closest comparison (i.e. OSX/Safari), it looks like Windows/IE is doing a little better with respect to the duration of the platform support. The version of OSX released at the same time as Windows 7 is Snow Leopard (10.6) and it doesn't look like it'll be getting any more Safari updates (last one was 5.1.7 in May 2012, current is 6.0 on 10.7 and 10.8 only). [1] http://en.wikipedia.org/wiki/Safari_version_history#Version_compatibility http://en.wikipedia.org/wiki/Safari_version_history#Version_... [2] http://en.wikipedia.org/wiki/Internet_Explorer_versions http://en.wikipedia.org/wiki/Internet_Explorer_versions