FIFA can't host 2 consecutive World Cups in the same Confederation. So China can try to buy 2026 or 2030 but those World Cups are not going to China. 2030 is the Centenial, hopefully FIFA does the right thing and takes that tournament back to where it all started, Uruguay. But it will more than likely be an Uruguay/Argentina hosted World Cup.
Not only can Uruguay not host for the reasons listed but they do not want to host. The only reason Brazil hosted was because FIFA was determined to have a South American World Cup. They opened the bidding and Brazil was the only country that said, "Ok, we'll do it."