14 DAY TRIAL // The development of Ubuntu 16.04 LTS (Xenial Xerus) has started, and we even know the launch date for it. We can now begin to track the Linux kernels that will be implemented in the daily builds.
The Linux kernel is a very important component, and the final version implemented in Ubuntu is usually of interest. Right now it's way too early to tell what version of the Linux kernel will eventually power Ubuntu 16.04 LTS, but if history is any indication, a new and major release will probably be made after the operating system passes the kernel freeze milestone.
Ubuntu keeps the same branch of the Linux kernel, even if newer ones are made available after launch. The only exception to this rule is for point releases of the LTS branch of the OS, which also bring newer Linux kernels. Until now this has been the only way to get a newer version, although it's quite possible that things could change.
There is a discussion going on right now among the Ubuntu developers to allow important updates past the gates after the launch of the OS and that would be a really big change for Canonical's OS.
Linux kernel 4.3 is just a start
During the development cycle of Ubuntu, the developers integrate all the latest releases, and that means even the RCs that are made available by Linus Torvalds every week. It will be a while until we can use the latest Ubuntu 16.04 builds in relative safety, so until then we'll just have to catalogue the kernel upgrades from a distance.
It's also important to know that the launch date for Ubuntu 16.04 (Xenial Xerus) has been determined already and it's going to be April 21, 2016. Also, the first daily builds have been proposed as well, but for now they are pretty much like Ubuntu 15.10, and there is not much to see.