It should just be its own spinoff of SCV or whatever next installment, rather than being included in the main game, because of the obvious development reasons, or more like I wouldn't think PS would have the time and money for it to be in the main installment. Would be very nice to play though, and I would surely buy it.
CaS does need its own game though. The very reason Creation was introduced was SC3's Chronicles of the Sword, and the huge amount of guest characters. Since CotS is gone, there is no substantial purpose for Creation besides it being a Casual quirk.
You said "you can't combo in DW" meaning Dynasty Warriors, in general, but I suppose.