Well, among all the fighters that PLAAF currently has and will be having in the next 5 years, J-10b is still the top-of-the-line fighter. I don't see China thinking about exporting J-10b until any 5th gen fighter gets deployed. J-10A for export? perhaps when J-10b comes on line. Definitely not J-10b in the next 5-8 years, IMO.
About China's export being better than what they had. That used to be the case because China was looking for approval internationally and wanted to show to the world that what they had was not as bad as people thought. So they went out of their ways to accommodate their clients. China no longer needs that kind of approval and China has the confidence to say to their potential clients "sorry dude, we will keep the best to ourselves. Don't like it? too bad!"
Any J10Bs sold to Pakistan will have different radars and avionics to what China will be fielding, so the risks to security isn't that high.
I have no idea what you are talking about with the 'seeking approval' idea. The main reason Chinese companies made huge concessions that most others won't even talk about was because of how backwards China was technically. Back then, the only way to make Chinese fighters a realistic choice was to allow the integration of foreign radars, avionics and weapons onto Chinese airframes because Chinese electronics was just not good enough.
Export orders was also far more important back then because of how poor China was, and every dollar earned in exports was a pretty big deal.
However, even then, China still maintained its principles and turned down the Iranians when they wanted the J8II.
However, because the J8 was considered the top fighter, CAC was allowed to export J7 models that were better than what the PLAAF was fielding. The F7PG with its two piece canopy and double delta wing was first exported to Pakistan before being fielded by the PLAAF as the J7G.
With the J20 in flight testing, I see the J10B as being in a similar position as the J7G in that it may well be exported before the PLAAF gets them.
China won't be pimping the J10B openly on the international market anytime soon, but I think for Pakistan, an exception can be made. There has been far too much talk from highly placed named sources within the PAF for far too long for it all to be hot air.
I think originally, the PAF was supposed to have gotten the J10A years ago, but they delayed that order when they got word of the J10B.
The J10B itself may even have been delayed as a result of suggestions made by PAF pilots based on their experiences with the F16Blk52 and or M2K-9s.
Pakistan only has a developing aircraft production industry, but its pilots have first hand experience with some of the best fighters in the world from PAF service, and also from being loaned out to Gulf states like the UEA, so their suggestions would carry a lot of weight and it would be well worth China's while to take what they say onboard. I think CAC already learnt how useful such advice and suggestions can be from the JF17 project, and as such, I would not all be surprised if they continued that understanding with the J10B.