Sounds like another side effect of the /usr/sbin transition. Juan's suggestion helped with my nvidia problem, it might work for you as well. Make sure your /usr/sbin directory is a symlink to /usr/bin before you do anything else.

- dkms build -m virtualbox-ose -v 5.0.2 -k $(uname -r)
- dkms install -m virtualbox-ose -v 5.0.2 -k $(uname -r)
- xbps-reconfigure -f virtualbox-ose
Before running xbps-reconfigure, make sure the kmods are built and installed correctly.