We already have some arctic maps that feature parts, filled with trees.
I liked those places - they change combat and spotting dynamic, it feel fresh.
More places to hide, maneuver and flank. Less spotting and sniping, more searching, reaction and coordination. Harder to mass shoot something, more use of close combat weapons.
We already have most, if not all, tiles needed for that.
So, a few new maps mostly filled with trees, rocks, wilderness and less clear open space would be good to have.