We're on the normal schedule for 4.16 and everything still looks very regular.
rc3 is larger than rc2 was, but as mentioned last week, that's expected - rc2 really was tiny. People have started finding things to fix, but there's nothing that really stands out as particularly scary here.
"Small changes all over" is the word.
About half the changes are drivers (networking, rdma, scsi, usb, gpu), with half of the remainder being core networking (most of it netfilter, but it's all over). The remaining 25% of the patch is "misc" - arch fixes, core kernel and vm, security subsystem, and tooling being the main stuff.
The appended shortlog gives an overview of the details for interested parties.