I am unsure how good a strike platform the B will be, it maybe too short rangedwell initially PAF was looking at around 150 JF17 + F16 100 + and keeping Mirage till some thing new comes along.
but things changed in 90s than came 2000 and things started to change but along the line it all changed again.
Throughout this JF 17 also evolved from 150 to 200 to 300. and yes logically it will change again. PAF was reluctant to inducted J 10 C and along with others things one factor was that it will need revisions of induction plans again and cut in JF 17 is possible or either an entire change of roles. It is also possible that PAF will now look at JF 17 B to augment strike capabilities rather than a multi role one.