Its seems like there's not really any historical route though, at least the Egypt they've shown had two path that didn't really follow history, with the default being definitely not historical, it seems like they went purely from a geographical point of view ("oh Egypt is in Africa so I guess they'll become the next African civ").I watched the 26 min official video. And I do think the purist would definitely stick with more historically-accurate route, meanwhile some would definitely get creative with their choices. But I feel for each age advancement, you can only stay pure to one civlization. Not to mention, this will create balance issues, as it always happens with any multiplayer games that offer build variety.
One other thing I'm dying to know is who will be the composer? Hoping it's Chrtistopher Tin again
It's a very strange choice because the opposite would have worked much better, pick civ and leader separately, and change leader once in awhile (ie egypt lead by Napoleon and then Churchill).