That would changing in the future. you can see it, if you see closely China Military development in recent years.
China is So Powerful today, and they have Good Power Projection Power.
China, Pakistan, Russia, and Iran is alliances.
and if they have Common enemies, I am sure China will send somekind of Joint Ops.
China is Unpredictable Country.
One week before Chinese Intervention in Korean War, if you ask American,
'there is any chance China send troops to help North Korea against us and allies?'
The answer is
Big NO !!!
China just torn by 8 years war from Japan Aggresion and 4 years war in Civil war.
and they would not dare to fight against the strongest country in the world that time, who have Atomic Bomb, and the Winner of World War 2.
But History tell the other thing, Right?
They Push back U.S Troops and Allies back to Pusan.
China is Unpredictable because they keep Low-Profile, even though they are already as Powerful today.
China is so Powerful today, no doubt.
And No One in here can Predict what China will do in the Future with their Powerful Military.
History Never Lie.
Time will tell us.
The problem is, you cannot look beyond the epidermal layer of an alliance, then you may as well form an [Insert US Enemies here] Alliance.
In the next 10 years, China is going to be transitioning from developing country to developed country, and this rate, the international cooperation (Not just US but rest of the world) are very important. It cannot be said to a tune of the country like Iran and Kazakhstan, which they literally have nothing to lose, would China or Russia be actively antagonizing the West or US just because Iran or Uzbekistan or Kyrgyzstan wanted to express some of their frustration?
NATO only works because all their member are a responsible regional power and while they all face a common enemy - Russia, you will not see NATO asking Iraq or Jordan to join them, even tho both country were next to Turkey, a current NATO member. That's because if you have to form an alliance to a selective amount of country, you cannot do with some that are risky and being a wild card is not exactly what you are looking for as a Alliance material. What if Iran drag China into a proxy war with the US with the like of Turkey, Iraq or Saudi Arabia? There are nothing to gain for China, while nothing to lose with the US either. But if China refused to help, then it would shatter the credibility of said Alliance.
Another thing, History never lies, but you are wrong on the history bits.
China never went pass 20 Km south of Seoul during the Korean War. Strictly speaking, not further south of Imjin River. The Chinese involvement in Korean war after US/UN troop went all the way to the Yalu River, which bordering North Korea with China, then China intervene on behalf of the North.
North Korea had indeed push ROK Army into Pusan perimeter, but do bear in mind When the KPA force the ROK into Pusan Perimeter, the War is relatively new and there were simply not enough US/UN unit to defend the line, and only about 30,000 US troop (The number garrisoned in Japan) were in Korea at that time, facing 120,000 to 150,000 KPA troop. You cannot technically say US/UN were involve at that early stage. US/UN troop got into full strength at Nov 1950 at 400,000 troop, 2 months after the Inchon Landing.
Another aspect about Nuclear Weapon, China were under Soviet Nuclear Umbrella at that time, Truman was asked again and again by MacArthur to use Nuclear Weapon on China in 1951, he won't because it will almost certainly leads to Soviet retaliation. The US did not use nuclear weapon in Korean War not because China have some sort of magic that disallow them, but because of Soviet Union. Had the war begin 1 year earlier, where the Russian had not yet got the bomb, pretty sure Nuclear Weapon will be use in that sense.
thats what an alliance is, a group of countries. just becuase one country in an alliance does not like the decision of the rest of the group doesnt the rest have to simply stop and convice the reminder to get on board. think of it like this. syria. china like russia does not want assad to fall and see it in the hands of a nato controlled puppet government,like urkraine. it may not send ships, or jets or put boots on the groud, but it will help via iran and sending weapons to syria via russia and iran. also now that i think of it a group on the scale of nato is a bad idea for the reason of possible diagreements and possible internal bickering by a possible conflict between india and pakistan or anything else. i think a secret pact, which would be more suited as countries can be more flexible and would be seen less as a threat to other countries.
Well, if that is the case, it would not be in any sort of alliance, I don't see why China cannot send help directly to Assad without routing thru anyone. I mean even if China send weapon underground thru Iran, it does not actually construct anything other than their own perception we had already know.
The question about an alliance does not actually lies on India or Pakistan, but rather the smaller country would have use the Alliance to settle some score which directly or indirectly would drag other member into any unwanted fight, the purpose of an Alliance is to set up a defence on a common goal, I cannot see how the said alliance would have any sort of common ground. Some dislike US, some liked the US, some were neutral. And even China, per se, literally cannot afford to antagonize the west, particularly the US at this stage, unless the US have become an moot point on world stage, China basically cannot be hostile toward the US, at least openly. And when US reach that point being irreverent in world stage, the purpose of said alliance would have been gone completely. Hence there are basically of no use of said alliance. Beside some day dream scenario with some PDF member mind.
IMO Modi's India has been both an opportunist and a fence sitter. We all know that e.g. Modi's sudden trip to Russia on Dec. 24, 2015 alarming Obama. That is why both USA and Russia never truly trusted her anyway. 
