[Inziladun]

Welcome to the Downs, Uruk's Bane!

Aside from Aragorn, known to Sauron as a claimed Heir of Elendil, I honestly wouldn't think the rest of the Northern Dúnedain would have been thought a serious threat to him.
Their numbers were so greatly diminished that, skilled as they were, they were no real impediment. After all, they had been unable to even prevent the Nazgûl from entering the Shire earlier.
No doubt Sauron would have taken pleasure in utterly destroying the Dúnedain from North and South when they were gathered right in front of his gates, but I doubt he had thoughts for any of the remnant of the Men of Arnor by name except Aragorn.