The overwhelming popularity of GitHub continues to lead to the demise of other, often much older project hosting sites. The recent confirmation of a 2015 announcement that "Kenai.com site will be closing permanently on April 28, 2017" and associated Java.net Forge Sunset is not terribly surprising given the previous shuttering of once-popular project-hosting sites such as Codehaus and Google Code. Back in 2010, there was the blog post announcement that Project Kenai was moving to Java.net after originally apparently communicating plans to close Kenai to outside projects.
Some projects have already moved (starting in 2010 with the previously mentioned announcement that was changed later) or have begun moving off of Kenai and Java.net and most of them, not surprisingly, seem to be moving to GitHub. Examples of these include Java Native Access (JNA), jawr, and MonkeyBars.
It has been proposed on Twitter that "It would be a nice move from @oracle to move the JSR content from http://kenai.com and http://java.net to #github" with some brief Twitter discussion on what this would entail.