I live in China, here are my thoughts....
KFC should continue to grow steadily, it's always packed. Chinese people don't want Western food, they want the Western level of service and supposed safety/cleanliness. So, apart from the original chicken (which nobody eats) the menu is completely different, with super spice, grease and MSG, even more than the USA.
Chinese people don't like Western food, and they care even less about Mexican food. If they update the Taco Bell menu with super spice/grease/MSG, then they are just competing in the same space as KFC, which is already built everywhere. "I want to eat some Mexican food today" said no Chinese person ever. For them, KFC and Taco Bell will be the same.
Pizza Hut... the market for overpriced, bad pizza is dying.... they slashed prices, and seems also slashed the staff, the service and cleanliness is going down the tubes. Now other Chinese or foreign brands are easily a better choice. On the cheap end, there is Saizeriya from Japan, growing like crazy, menu is literally 1/3 the price and food arrives in 5-10 minutes, instead of waiting 30 minutes at Pizza Hut. On the more expensive end, there are a lot of places popping up where you can get a much better $20 pizza than Pizza Hut.