If china can installed local avionic on Y20, i see no reason for them not to come out with a civilian version. It technically within china's ability but problem lies with market acceptance.
Using Western avionics and parts is to connect to the mainstream global aviation market. Airlines don't need to train another batch of Pilots and engineers to handle the unique Chinese avionics. That will be too much of hassle and makes it unattractive to the foreign buyers.
Other than this you still have the problems of getting the plane certified by FAA and other aviation authorities worldwide . Using too many local parts only complicate and slow down the process.
We can only take things gradually. The important things is to get the plane certified and market acceptance. Once it done than we can talk about slowly replacing foreign components.
