According to Linus Torvalds, things appear to have calm down lately, and Linux kernel 4.7 Release Candidate 5 is a fairly normal milestone that consists of approximately 50% updated drivers, in particular GPU updates, but also various improvements to some hardware architectures, including PowerPC (PPC), x86, and ARM64 (AArch64).
Of course, there are also the usual patches to fix various issues for some of the supported filesystems, as well as for things like scheduler, mm, a few sound drivers, general-purpose input/output (GPIO), Xen, hwmon, as well as RDMA (remote direct memory access).