We will see how the PRC (China) when the choice becomes either the USA or Iran. If China wishes to co-exist with the USA, it will drop Iran in a New York minute. The big guys in the world to come are the USA, the PRC (China) & India.
Red China was an ally of convenience in Iraq; they got the oil and they got to aid Iran in the process. There is no trusting a communist state; one can only make a show of power to make them go along with you, but they could never be a true partner.
And if India regresses to its past socialistic proclivities and gets closer to Red China than the USA, it’ll be to their detriment too.