I think many of players would love to see such a complete edition that would cover not only Empire but also other parts of the Old World.
And yes, a good way of publishing it would be to make a thick core rulebook (about 400-500 pages) in hardcover. In that one You would find all the information You need to play and have fun for many hours. It would cover mechanics, geography, races, base and advanced careers and of course a small bestiary. Then each expansion would expand the knowledge about some places, thing you can fin there and special careers to that place, all with a small adventure set in the described place. So on the session You would only need to have the core rulebook with dice and eventualy bestiary or supplement fiting Your adventure.
That would be a game of my dreams!
If FFG will do nothing about that then maybe it's time to start working on my own edition of WFRP with a lot of house rules.
Cheers
PS. When FFG got the licence then maybe they still have the rights for WFRP 2nd? If that's true then why wont they make a special edition of that game bounded in a series of thick hardcover books with all that was published for it. Nothing new they will have to create and still would got money from sales. This maybe would not fix the situation but would give some players a chance to get things that they missed.