EB is a realism mod, afterall, and would always remain one, if there ever was a EB 3 to be, and it is one of the first things to remember. Speculation about the existence or the amount of contact of ancient europe with regions like China or - more notably in this context - America is allowed, but the assumption of a successful military expedition is beyond anything conceivable.
EB 3, if it is going to be, should focus on a map of similar scope as the actual one and try to use the additional possibilities for more detail in that area.
It might be fun to fight meso-americans and chinese with roman legions, but that is a thing for a different mod, not for EB.

So, let's just hope that the Empires-engine allows for ancient combat and that a qualified team of modders will find to carry the torch of Europa Barbarorum even beyond EB II.

Sorry if I'm repeating something already said, I haven't read all.