well, not sure about just B itself, but J-10 from this point on should have at least 5 years of production 2014-2018) before J-20 starts mass production. If they build an average of 35 a year, that would point to a production run of 165. After which point, it may decline to a regiment a year. At some point, they will move to J-10C. I'm guessing 5 to 6 regiments is probably reasonable number.
Is there a J-10C project actively worked on? Around 2020s I think it will be J-20 and J-31. I don't see the reason to keep producing J-10, bar export customers, when you have these two 5th generation production lines are running.