I'd expect them to open source various components of it before they open source the whole shebang. I.e., I'd expect to see them put Chakra out, maybe the browser chrome, the parsers, etc. before they put out all of edgehtml.dll. I could be wrong.
Edge (and particularly IE) are fairly heavily tied to the OS in a bunch of places. IE, for example, can do weird FTP and Windows Explorer stuff. The infamous "Internet Settings" dialog and the way IE deals with stuff like proxy servers is only sort-of part of IE. IE's network stack is largely dependant on the bits and pieces available in the OS below (consider IE11 can only use SPDY on Windows 8). I wouldn't be surprised if open sourcing the browser wholesale would start unraveling a lot of things that MS doesn't intend to be public.
Edge (and particularly IE) are fairly heavily tied to the OS in a bunch of places. IE, for example, can do weird FTP and Windows Explorer stuff. The infamous "Internet Settings" dialog and the way IE deals with stuff like proxy servers is only sort-of part of IE. IE's network stack is largely dependant on the bits and pieces available in the OS below (consider IE11 can only use SPDY on Windows 8). I wouldn't be surprised if open sourcing the browser wholesale would start unraveling a lot of things that MS doesn't intend to be public.