I have found a dirty way to make ar3012 and perhaps other stuff initially supported by this kext work in 10.13.6.
No VM or other crazy methods are needed.
What I've done is I installed 10.12.6 usb kexts over the original:
I should point out, that such a barbaric method can break stuff, but it didn't my case.
Prone to be broken after even security updates. If such is the case - eat, sleep, dance, repeat.
I cannot fathom, why the developer cannot opensource it even though he's out of the scene.