John McDonald (Key engineer behind VACnet) has offered to extend the service to other game developers, to the point of even publicly requesting partnerships at a GDC event.

Valve is intentionally vague about its anticheats, yes, but that is because each implementation is somewhat unique. TF2's, for example, was almost cracked completely open through analysis of the source code leak alongside pattern detection of bots and previously banned players until recent events.

It's believed that Dota and CS both have their own unique spin on how they do things, with I believe CS being the primary arm for VACnet to be tested on, and I would imagine it's not a drop-in solution for any game developed outside of Valve. They are open to partnerships though, so who knows?