One of him or Junaid are a must in the side. He is a right-armer so would be a welcome addition in our left-arm pace battery.
Tall Irfan is done now. His height offers no advantage anymore and he clearly lacks a bowling brain. Age and fitness not on his side either.
As far as Sami goes, I'm more clutch than him under-pressure. Far too inconsistent, unreliable in crunch games (basically rules him out of WCs, so what's the point), and age is not on his side, either.
That leaves us with Amir & Wahab for all formats. 3 more pacers are needed for each format.
For Tests, we have Rahat, Imran, and Adil doing fine.
For ODIs, I think we should have Sohail Khan, Amir Yamin, and one of Junaid Khan/Hassan Ali/Rahat Ali/Ehsan Adil/Zia-ul-Haq.
For T20Is, I think we should have Junaid Khan, Amir Yamin, and Hassan Ali/Zia-ul-Haq.
Just FYI, Zia was dropped without getting a game in the T20I squad vs SL.