This announcement is significant for multiple reasons. First, it means that authors of applications using Gears will need to adjust their code for this eventuality. Second, this move serves as evidence that Google feels that HTML5 support among popular browsers is or soon my be sufficient to no longer need Gears. Indeed, Aaron Boodman ends the announcing post with this statement:
Our mission with Gears was to enable more powerful web applications. Over 5 releases, we added tons of APIs, enabling everything from offline access to parallel computation. Now that these features have all been adopted by browsers and have official W3C specs, they are available to more developers than we could have reached with Gears alone.
If the major browsers being to uniformly support these modern web application features, the standardized availability of these functions over use of a plug-in will certainly be welcome.
For those wishing to use Gears functionality past its support timeframe, Boodman reminds us that "the code itself will of course remain open source, and anyone is free to use it."
In Goodbye, Google Gears (Sniff!), Harry McCracken predicted (1 December 2009) the demise of Gears at the hands of HTML5. Besides the original Google Gears blog post warning about that this day would come, RIP Google Gears also recommended (in February 2010) that developers start looking for HTML5 alternatives to their Google Gears use.
There are numerous other posts analyzing what the now realized Google Gears Stoppage means: Death of Google Gears Makes Cloud Backup Harder, The End of Google Gears?, Google Says Farewell to Gears Project, Good-bye Google Gears, Hello HTML5, Google Gears Death Announced, and Google to Retire Gears in Favor of HTML5.
I find the just-referenced collection of posts interesting because they cover my mixed feelings on this announcement. On one hand, it is pleasant to think about having a standard-based, built-in mechanism for the features previously provided by Gears. On the other hand, it is always less than comforting to count on future browser consistency in implementation that is "almost ready." Sometimes, a bird in hand beats two in the bush. Because browsers without requisite HTML5 functionality will be used to some degree for some time even after these newer browsers come out of beta, many web developers can expect to need to use object detection to detect HTML5 support and fallback to Gears, Flash, and other alternatives for some time to come.