Allies being a big part of the next fantasy has been pretty much confirmed by all "in the know"
The question is how heavily it will go that way.................
Okay, admittedly Fantasy is not something I regularly keep tabs on...but part of me thought it would be an extension of the whole "Forces of Order/Destruction" thing in the 8th Edition book.
If that rumour is true, then it means we may well see books like "Kingdoms of Men" coming out, as well as the Undead Legions book (assuming it is a book). Which probably also means you need to use that specific Army List to field Nagash, or possibly Arkhan.
On the one hand, it is different from the method used in 40K. On the other, well...I think the flaws are apparent with this system.