Firefox 3.5 might be only three months old, but fact is that Mozilla is already contemplating the early death of the browser version. The reason? Nothing other than the upcoming minor update for the open-source browser, scheduled to drop by the end of this year, namely Firefox 3.6. Following the general availability of Firefox 3.6, it will make little sense for Mozilla to continue offering support for both version 3.5 and 3.6. This is why the early death of Firefox 3.5 is already being contemplated, even though the browser was launched at the end of June 2009.

Chris Ilias posted an interesting question to Mozilla: “As I understand it, Firefox 3.6 will be treated as a minor update to 3.5.x. Does that mean that there will not be any 3.5.x updates after 3.6 is released?” The answer he received came from Mike Beltzner, director of Firefox at Mozilla Corporation.

“It's not 100% decided yet, but if we issue a Firefox 3.6 as a minor update, then yes, we'd stop supporting the 1.9.1 branch at that time. There are several confounding issues with this approach, however, the most notable being that Seamonkey and Thunderbird will be based on mozilla-1.9.1,” Beltzner stated.

1.9.1 is a reference to Gecko 1.9.1, the underlining rendering platform of Firefox. While Firefox 3.5 is based on Gecko 1.9.1, Firefox 3.6 is based on Gecko 1.9.2, the next iteration of the open-source rendering engine.

The inherent downside of a fast-paced development process is the fact that the version number of Firefox will change twice this year, generating modifications throughout the ecosystems of add-ons for the browser in order to deliver compatibility. The end of support for Firefox 3.5 will force users to upgrade to version 3.6, or keep running a browser that will no longer receive security and stability updates.

Firefox 3.6 is currently planned for general availability in November 2009, and users should get ready for a similar minor update experience in the first half of 2010. Firefox 3.6 will be succeeded in just a few months by Firefox 3.7. And Firefox 3.7 itself will be replaced by Firefox 4.0 in October 2010 at the earliest.

But Mozilla traditionally keeps major versions of its open-source browser alive for a maximum of six months after a new major version of Firefox is released. It is the case of Firefox 3.0.x, which will no longer be supported as of January 2010, six month after Firefox 3.5 was released.

The latest releases of Firefox for Windows are available for download here.