Being an LTS release and all that, most OS vendors would want to implement it in their Linux kernel-based operating systems as soon as possible. However, it most certainly isn’t the easiest of tasks, as they need to run an enormous number of tests to see if the new kernel packages do not break anything in the user’s computer.
A few pioneer distributions have already started to test Linux kernel 4.4 LTS on their testing/unstable repositories, and will soon release them to the stable repos for the rest of the world. This is the case of Ubuntu, Arch Linux and Slackware, all of which have announced plans to add the new kernel in their upcoming OSes.
Ubuntu 16.04 LTS is still based on Linux kernel 4.3, and so is Arch Linux
At the moment of writing this article, we’ve checked both our Arch Linux and Ubuntu 16.04 LTS (Xenial Xerus) installations, and we can confirm that they remain based on the Linux kernel 4.3 branches, version 4.3.3, to be more precise. Moreover, the upcoming Linux kernel 4.4 LTS resides in the unstable repos where the devs do all the testing.
As for Slackware, we reported a few days ago that its development team released for testing the first Beta build of the upcoming 14.2 version, which integrates Linux kernel 4.4 LTS. Of course, other distros will follow soon, and it is the right thing to do because Linux 4.4 is a long-term supported kernel with the most advanced GNU/Linux technologies.
We don’t yet know when Linux kernel 4.4 LTS is expected to be released to the stable repositories for the aforementioned operating systems. The Ubuntu Kernel Team announced that they would add the new kernel version to the stable channels shortly, but looking at their release schedule, it might take a couple of weeks. Rest assured that we will inform you here if that happens.