> Anyway, circuits are more expensive than just running a packet-switched network lightly loaded.
This was undoubtedly true (and not even close) 20 years ago. As technology changes, it can be worth revisiting some of these axioms to see if they still hold. Since virtual circuits require smart switches for the entire shared path, there are literal network effects making it hard to adopt.
The old and new standard ways to do virtual circuit switching are ATM (heavily optimized for low latency voice - 53 byte packets!) and MPLS (seems to be a sort of flow labeling extension to "host" protocols such as IP - clever!).
Both are technologies that one rarely has any contact with as an end user.
Sources: Things I've read a long time ago + Wikipedia for ATM, Wikipedia for MPLS.
