Provided you don't import old comments it should be fairly simple. On the initial migration, the module could inspect all existing content types and alter them to remove the content part and add your own. The only one that may not like this is blogs
because that's comparatively old code. But anyway you encounter difficulties removing comments from anything including blogs that's a bug: file it and we'll fix it.
apart from that disqus is just a script tag so that part should be trivial to add.
Let me know how that goes and if I can help.