Its possible but you might have some mods to do. Firstly, if you just do the rims and tires, factor if the brake caliper pads meet the replacement rims. Next is the spoke length. Your Schwinn 3 speed IGH is taller flanged, the front is smaller. But if you find a 3 speed 26in conventional complete wheelset with a 3 speed IGH you might be able to get it done. Also the fork end on the Schwinn might be slightly narrower lug to fit the replacement wheel/axle. Simply file evenly the rearward sides of the fork ends. You don't want it crooked or offset, the idea to keep the material 'meat' on the top of the fork end (some refer to as the dropout). Hope that makes some sense.

I like your approach to having a wheel swap, regardless how done. Greatly helps future tire selection.