I don't think I was around when the decision to drop IL was made. NAPT devices in particular didn't like it; among other things, its port numbers are in different places in packet headers than TCP's and UDP's. I don't think an IPv6 version of IL was ever created either.
I'm not exactly sure what Brantley's question is. We've still got emelie and choline running Ken's file server and serving only 9P over IL, but I'm moving their data into fossils and ventis as quickly as possible. The other file servers (e.g., edith, martha/sources) are all fossil/venti or vacfs/venti servers serving 9P only over TCP. So some of the data seen externally is ultimately fetched via IL, but that's a small fraction and getting smaller.
