I can't see boneworks being gmod VR just due to the complexity of the physics calculations being overwhelming, imagine filling a barrel of shit in gmod and wiggling it, then imagine a barrel full of fully jointed monkey ragdolls in VR and wiggling it
I think HL:A has more chance of being MP as well- hand only physics, good engine for it, ect, while Boneworks will just have good sandbox mods and overhauls if anything.