As you may know, Greg Kroah-Hartman, one of the kernel maintainers, has announced that Kernel 4.4 will be a LTS (long term support) release, meaning that the system will be maintained for a bunch of years.
The official announcement:
“The Linux 4.4 kernel will be the next LTS (long term support) release that I will maintain for 2 years,”
While Mark Shuttleworth has not confirmed anything, most likely, Ubuntu 16.04 LTS Xenial Xerus will be using Kernel 4.4 LTS as default. This is quite good, since Ubuntu Xenial is also LTS, being supported for a lot of years.