You have to agree selling military equipment need political leverage. Just like how Turkey has chosen HQ-9 missile but under heavy pressure from Europe. They are force to cancel it.
Seriously, China is not keen to sell J-10 fighter overboard. How many foreign airshow has it participated to demonstrated its individual performance? Even it don't clinch a deal. It will not even affect J-10 abit. It is the chosen fighter for PLAAF.
If you read the janes article, PAF chief has say they are interested to buy Su-35. In fact, it's PAF needs to pay China middleman money to help them procure Su-35. As Russia has no objection selling Su-35 to China. Once the item belongs to China. China can do whatever China wants with it, including gift it to whoever.