Probably unlikely to be added in the core (esp. HTTP/2), but an HTTP/1 implementation could be done in pure janet - there is a binding of just a parser here: https://github.com/andrewchambers/janet-pico-http-parser
But yes, at some point a canonical replacement for circlet that was MIT licensed and event-loop friendly would be nice.
I am aware that there are already libraries that cover these to an extent like circlet and halo for http. Joy also features an http client. Maybe it's outside the scope of the project, but I think an http server and client as part of the core would really add to the utility of Janet. It would also answer some of the licensing questions for distribution if these were included directly in Janet core. For example, circlet is MIT, but it is based on mongoose is GPLv2.
Also, seeing Janet on HN a year or so ago was what got me to watch The Good Place, so thanks for that as well.