No, actually incorporating China into what we know so far about I:R makes plenty of sense.
- There's not really a similar concern about performance. The way CK2 worked, each additional county added dozens of characters to the game, which is why RoI was so much more taxing on release. (But later optimizations have made current CK2 run faster than pre-RoI CK2 did). I:R will have many times fewer characters and probably have to run a lot fewer character checks because the game will not be as character-heavy as CK2.
- There's no similar problem with China being too alien to represent with a feudal political system. A generalized political system that can represent Celtic tribes, Carthage, Rome, Epirus, the Diadochi and Maurya will be adaptable enough to represent Warring States China.
- Unlike the terrible prospect of inserting the peak Tang or Song Dynasties into CK2, the geopolitical situation in 304 BCE fits perfectly well into the theme of the game. China starts out divided between 7 major states, and while Qin is ascendant its total victory is not yet inevitable (quite analogous to Rome vs the rest of Italy at the same time, really). And if China gets unified, it will be beset by the same kind of inner power struggles and civil wars that will need to be modeled for Rome and the Diadochi.
I think the inclusion of not only India but also the Tarim Basin and Tibet in the base game make it pretty clear a China expansion is in the cards (and CK2-style China/Silk Road events are likely to be in the base game). And that's exciting to me, because I love Warring States China and I never thought there was a chance of actually seeing it represented in a commercial game.