Pakis will sleep with anyone and everyone against India. It is not a zero sum game. Having a 'friendly' regime in Iran will solve a large chunk of the Baloch problem for them. They can sell this to China as securing the region for CPEC. How Russia fits in, I don't know.
Thats my point ...
Russia want Iran ,and current Syrian crisis shows they are growing as strategic partner , China for now want to use Russia's strategic partnership with many nation as a successor of USSR as a asset of his own to create an Anti-USA block and step by step capturing leadership of the block effectively from Russia with ever growing and strong economy.
So Iran will be a very powerful future asset of Chini-Russia block towards which Pakistan try to shift themselves...
No condition can guarantee a Pak friendly govt in Iran ,even Afghan Taliban ,a puppet of ISI refuse to acknowledge Durand line when they are in power...
Any change in Iran will bring uncertainty to Pak for sure , like Afghanistan,88 ...pakis are the one who have to suffer the leftover of anything wrong happens in Iran..Q is to whom in future they gonna blame for it , China or US ?