Well, the big problem I see is that even if China lifts the transit ban on its citizens, CI and BR still won't have enough frequency or rights to really serve transit traffic to places like XMN, FOC, NKG, CSX, KHN, or WUH. In order for this to work, each airline will need to have minimum double daily service to all the 2nd tier cities south of PVG and north of CAN.

The current bilateral air service agreement is highly restrictive and most stations don't even see daily service even with code share.

That being said, a lot of these Chinese cities will probably benefit from being able to transit in TPE. For example, XMN-TPE-LAX on a single CI or BR ticket is probably a lot easier to do than a mixed MF-CZ itinerary that involved backtracking XMN-CAN-LAX.

But then the question you have to ask is... why would the Chinese airlines want to see this happen? What does CZ (which will be impacted the most) have to gain from this?