Interesting that you mentioned Mohammad Hasnain. I have doubt about the future of his career, as he was reported for suspect bowling action. He managed to clear his action later and right now is representing Worcestershire in England county cricket. Haris Rauf is a good bowler, but I would rate Hasan Ali ahead of him. Anyway, there is no shortage of fast bowling talent in Pakistan. New players are emerging, such as Shahnawaz Dahani, Mohammad Wasim (North Waziristan), Zaman Khan (Mirpur) and Mohammad Imran (Swat).
You have great insight of Pakistan cricket. There are so many fast bowlers but only one quality fast bowler which is shaheen. Hassan Ali is what kohli is for India. Hasnain has cleared action, again I would say just give some time to prove himself.