modprobe: FATAL: Module wl not found.on Macbook Air running Kali Linux 4.3 trying to setup Wifi
I was having the same problem, and finally found a way to fix it. Run this script that download the necessary headers the missing module.

https://gist.github.com/speeddragon/2d4ea420a8a53407cb8218fa28c2a74b

I didn't test the script, but it should work.

The issue is the following. Kali doesn't show available the 4.3.0 linux-headers and necessary packages (like kbuild) to build the module when you install "broadcom-sta-dkms".

After install the necessary things for 4.3.0 kernel, you install the "broadcom-sta-dkms" again and "modprobe wl" should work.