Do fully rolling_release distros like ArchLinux, openSUSE, Alpine and so forth include kernel-upgrades as part of their rolling upgrades?
Or kernel upgrades are a separate issue even within the rolling_release paradigm?
The kernel is just another package in Arch. When upstream pushes a stable release, the maintainer will package it for Arch.
The only special treatment the kernel, and every other package in the [core] repository gets, is that they are released to [testing] first, so that developers and experienced users with that repository enabled can report any issues before they are introduced to the general population of users.
Once a package--including the kernel--has sufficient sign-offs, it will be pushed to the standard repositories.