That was the starting point. I have been discussing a new JSON format with @ericzinda at Consider adding an option to use a different JSON Format · Issue #4 · SWI-Prolog/packages-mqi · GitHub
It is not very hard of course. The main issue is what you hint at: a lot of stuff will move and that has implications for the build process, users and documentation. We can minimize some of that by adding a library at the old location that loads and reexports the new library (and prints a deprecated warning). That is also what happened to the DCG support that started in the HTTP package as well. I’m still in doubt. The other option would be to simply minimize the HTTP package for the WASM version. That is far easier but doesn’t solve the long term issue.
One of the next steps is to be able to add the foreign libraries in the WASM version.