Erm... Correct me if I'm wrong, but isn't "advisory-only VC" an oxymoron? If you're not investing capital, you're not a Venture Capital firm.
I think that in many cases that might look quite similar to existing accelerators, except that accelerators generally target very early stage companies.
Sam discusses drops in the idea at the bottom of his post:
The best VCs are great, and they will probably continue to
do well. In fact, they’re so good that they could probably
get away with only selling advice—they understand how to
build big companies in a way that few other people in the
world do.