It's not really a black and white issue because you can have greater autonomy while staying a part of China. From what I can understand, some degree of regional autonomy was basically baked into the system when it was realized fairly early on that China was way too big and complex to be effectively centrally planned, and that a degree of regional autonomy was essential. I think it is only natural that these regions should agitate for a greater degree of regional autonomy, but if they break completely from China then they only leave themselves open to exploitation by other imperialist forces.