Montgomery insists Arsenal boss Mikel Arteta is a big fan of the Sweden striker.
He told ChronicleLive: "Mikel Arteta is a big fan and is desperate for a centre-forward.
"He wanted either him or Ivan Toney this summer but got neither. That won't put him off. He will return for Iask who would score a ton of goals in Arsenal's set up and become a fan favourite like Thierry Henry.
"That is why it is imperative Newcastle have a good season to persuade Isak to stay and that is why they desperately needed to sign this summer. They are vulnerable at centre-forward if Isak gets injured. Callum Wilson is a good player and can cover Isak no problem but can he be relied upon to be fit? After that it is down to a young lad from Sheffield United bought at £15m and it is impossible for him to do Isak's job right now."