In so far as China going for JF-17 Thunders is concerned, there is no reason to dismiss or accept the idea. When there is concrete evidence, similar to what came from of Pakistan (President of Pakistan's announcement that China will buy JF-17). Then we would have no option but to accept the news as fact. Mind you, one should not take it lightly, when the President of Pakistan makes such an announcement.
As for J-31, or J-20 or other various combat aircraft that China produces, are available for any of the three military services of China. It is based their strategic requirement and approval of the government, on whether any particular aircraft is procured for any of the three services of Chinese military. We are in no position to say which combat aircraft China would or would not procure. Let's not be childish here!
When it comes to Pakistan and China, both countries have mutual respect, honor and support for each other. There is a very strong and powerful historic alliance between the two countries. And anyone who attempts to discredit that, is certainly foolish and seriously lacks in diplomatic skills. So when people say China would never sell Pakistan this aircraft or that weapon. This sort of statement only reveals the amateurish sentiments of that particular person, nothing else.
Each country choice of weapon to procure or produce, depends on their financial ability, their infrastructure’s capability to operate/produce/maintain the weapon, the approval of the seller country’s government and their regional/international policy of arms sales. In Pakistan’s case, all of the above come into play when it comes to procuring any weapons’ system from any country. Be how it may, alliances alone do not determine whether Pakistan will go for or get which ever aircraft from China.
As of now, PAC’s priority is to manufacture JF-17 Thunders for Pakistan Air Force and both PAC-CAC are actively marketing the FC-1/JF-17 combat aircraft to various countries around the world.
Pakistan Air Force’s top priorities are to induct (250-300) JF-17 Thunders, which will have IFR, BVR, EWS, AESA and Data-Link capability. Pakistan Air Force also plans to field a fleet of 80-90 Lockheed Martin F-16 Fighting Falcons. Apart from this, they are also in the process of integrating the ZDK-03 Karakoram Eagle (AWACS) bought from China, along with SAAB-Ericsson Erieye (AEW). And along with these aircraft, there are various other new weapons platforms which are being inducted.
So to put the matter of J-10B for Pakistan Air Force to rest. When both China and Pakistan are ready, willing and available to discuss the possible sale of J-10B for Pakistan Air Force. Then I am sure all of us will hear about it in the news. Till that time arrives, I would stress that the ‘Nay-Sayers’ and the supporters of J-10B for PAF, refrain from making irrational remarks about the potential sale or with regards, to the Sino-Pak alliance.