Many fans were suprised when they saw Red Skull in Avengers: Infinity War, but he didn't do as much more than a cameo. According to sources, Red Skull will be back to face off Sam Wilson for Captain America 4.
Now that Sam inherited the iconic shield of Captain America, it will be a perfect test for Sam if he is worthy of being the new Captain America. Red Skull is also free, now that Thanos destroyed the Soul Stone in the main timeline, he can now leave Vormir and go to earth to face the new Captain America.
Marvel has yet to confirm Sam Wilson's Captain America 4 and it could be a long wait before we could see a Johann Schmidt comeback. The Falcon and the Winter Soldier is expected to premiere on Disney+ next year.