Is The Existence Of PAF Questionable? Answer is: No.
Look, the center of attention for our defense forces is India, and it will remain like this till every (most of the important ones at least) dispute between the two are solved.
Ask yourself honestly, can we really take on USA, all by ourselves? No. To say that China would assist us against US is absurd, why, because China won't help if we are intentionally to go head on against US, they would only help if US attitude and aggression rise to the level where they see their sovereignty and interests (resources, and routes etc) in danger, and I don't blame them for that (at least they would be with us in the latter scenario).
Don't you think that by engaging ourselves with US forces, won't encourage our rivals to try for a potential adventure against our country? Of course, this is always a possibility. So, can we really defend ourselves against multiple opponents at multiple fronts?
So the actual question here is whether we continue with the same policy to allow the drones to kill our people? This policy has to be reviewed and re-designed for the interest of our nation. Yes, we have to tough this one out against the super power, and demand to enforce whatever is the best strategy to go forth.