I am looking forward to it, but with no new models revealed along side it, not even Endless Spells or scenery, and the mention of old units going, then it's possibly not the book we really want.
it cover free cities armies, an expansion of the rules from Firestorm, so they're mixed species - Human, Duardin, Aelf, Sylvaneth, Stormcast etc. It's not a new "Empire" book as we might expect.
That said, it kind of appeals that each city they feature will have much more of a unique culture, much more so than Altdorf and Middenheim