Unfortunately there aren’t many options. I just don’t see anyone who can come in against the likes of Archer, Starc, Rabada, Bumrah, Boult etc. and score a 50 in 30 balls or something. Still you have to try someone. I think perhaps Khushdil Shah could be given a go. He is clearly a potentially long-term investment unlike Iftikhar and Asif Buttler Ali.
Or Pakistan could do something innovative and open with Babar and Imam, pushing Fakhar down to number 6. However, it would be a very bold move and we don’t do such experiments. It is especially unlikely when you have Misbah at the helm because his lack of flexibility is well-documented.
All in all, this position is a big problem for Pakistan and requires a batsman who can maintain 35@110 stats against quality opposition.