Does the Old Testament say God will deal with Israel again as a nation?

Yes, the Old Testament repeatedly promises that God will bring Israel back in His own time and will again deal with His national people. Though God providentially uprooted them for unbelief and dispersed the nation, He promised to restore them, so He is still going to deal with national Israel.

Les explains that after the separation of Jew and Gentile, God dealt primarily with the covenant nation of Israel through the Old Testament. Because they were stiff-necked and steeped in unbelief, God allowed the Temple to be destroyed in 70 A.D. and the nation to be dispersed, but He promised, 'I'm going to bring you back again, in My own time I'm going to bring you back.' Les says all the Old Testament screams of that, affirming that God is still going to deal with His national people of Israel. He also notes Palestine has always been the homeland of the Jew.

Why will God still deal with the nation of Israel?

God will still deal with the nation of Israel because He promised to bring them back in His own time, even after their unbelief caused dispersion. The Old Testament consistently affirms this restoration, showing that God remains committed to His national covenant people.