I myself spoke to a retired Air Marshal {Ex-PAF Chief} that PAF may ditch J-10B in favor of another much potent single engine air craft from CAC with stealthy features. He said that the project is still on the drawing board & all PAF Aeronautical engineers currently stationed in Chengdu for JF-17 upgrade , test & evaluation would see their stay extended for the new air craft . Allowing PAF to be part of this project from the scratch and input whatever they have learned from their exercises and exposure to the F-22 etc as well as bring their demands and knowledge to the program. He said that the new air craft would be highly advanced and would conform all features tailored for our needs -- more or less a PAF specific model.
He denied having any plans to induct a twin engine air craft any time soon. He added that we would direct resources to more force multipliers & 4 new high end area air defense systems [Long-Medium-Short Range]
There is a chance this new aircraft could be the JF-17 Block 3. The OP article talks about a pre-4th gen aircraft(pre-4th gen would mean a Rafale type aircraft or pre-5th gen in American system of classification). So, you can say the J-10B will come along with this Block 3 JF-17 which actually fits the description of the OP article. There is a chance the Block 3 would have higher priority over the J-10B.
I don't think there is nothing we know about considering what fits the pre 4th gen category. Even the J-10B can be modified to hold that status, but I am not so sure considering it is an older design(more of a F-16 Block 50/60 capability) compared to the yet to be designed JF-17 Block 3.
The concept design looks like the JF-17 too, with a vertical fin to boot.
As for the air defence systems. I guess Chinese systems are high on the list with HQ-9 being a topic of debate for long range needs.