First i will say that technically it’s already supported. You don’t HAVE to write headers, you can either just make them by using “makeheaders”. Allowing you never to have to write headers again. This is something i was looking to update to UE4 but i do not have time. OR you can just write your headers in cpp files, therefore no header files 
this is a joke, do not do this. even though you can
Yep, the module system has been around for a very long time, if they wanted it, we would have it already.