Okay, here is how I imagined what they could have done if they were to bring Red Skull back into the Marvel movies. I thought of this before Infinity War came out, so, obviously, some elements do not carry over, and considering how the Black Order/Children of Thanos were written and what happened to them, it wouldn't happen even if one just changed Schmidt's situation. Don't get me wrong; Red Skull appearing on Vormir long after many had given up hope on seeing him again (even if he wasn't portrayed by Hugo Weaving) was cool, but his role could've been filled by literally any other comics figure and it wouldn't have made a difference. I imagine my idea of being something truly epic and deserving of the character
This would probably be something that would go into the sequel. The Avengers are storming Thanos' flagship and have been separated. In this scene, Captain America is fighting one of the Black Order members. Let's just say it's Corvus Glaive. And there is another guy in the room, an armored man with his head covered by a helmet, although you could possibly see small parts of his face through slits if you got close enough and squinted, giving a possible hint that may become apparent later on. So, Captain America runs into Corvus Glaive, and the servant of Thanos challenges Cap to a duel.
Glaive's glaive connected with Captain Steve Rogers' shield as the servant of Thanos and the sentinel of liberty traded blows. After several parried strikes, Cap managed to catch the tip of the weapon with the edge of his shield, and twisted his arm to pull it from his foe's grip. Cap tried to attack as he twisted back around after disarming his adversary, but Corvus brought his now-free hand forward and lifted him up by the neck. The red-eyed warrior glared into Cap's blue eyes.
"You dare to fight your way through here, thinking you can defeat us all? You think yourself to be worthy of an audience with the mighty Thanos?" Glaive accused. "What makes you think you're so special?"
"Nothing," a new voice spoke. Glaive and Steve turned their attention to the armored man standing in the back. Steve had not paid much mind to the man before. He figured he was just a door guard. But, for some reason, the man's voice struck a chord in his mind.
"There is nothing that makes him special," the man continued, taking a few steps forward. Slowly, he grabbed his helmet and carefully removed it. As parts of his head were exposed, Steve could make out a red neck, then shriveled lips, and then a hole where his nose ought to be…
"He is just a kid from Brooklyn." With that, the man fully removed his helmet, revealing a bald head with shriveled, reddened flesh. Cap's eyes widened in shock. With Glaive's hand tight around his throat, he struggled to gasp. "Isn't that right, Captain Rogers?"
Steve found himself staring into the face of a man whom he had not seen since before he was frozen, a man who he thought had died right in front of him, disintegrated and banished to the void of the cosmos by the unmeasurable power of the Tesseract which he had used to power the weapons he designed for Hydra. To him, it felt like only seven years ago, but it was actually more than seventy, aboard a massive airship from which he had planned to drop bombs on several major cities.
That man, a symbol of such great evil, the face of the dangerous terrorist organization that had infiltrated S.H.I.E.L.D. at its core and caused so much death and suffering, stood in front of him.
"Sch…Schmidt?" Steve gasped.
The military scientist who had at one time been called "The Red Skull" smirked. "Now, that is a name I have not heard in a very long time," he said.
A tremor ran through the ship. Corvus scowled, noticing that the intruders were more disruptive than he thought. He dropped Cap, letting him gasp for breath. "I shall leave you two to become reacquainted," he said. He picked his glaive back up and walked out.
Cap stood up and grabbed his shield. His eyes met those of Johann Schmidt, who continued to walk toward him.
"It has been far too long, Captain Rogers," Schmidt said. "Has Hydra prospered in my absence?"
Cap glared at his nemesis. "Hydra's gone. The Avengers and S.H.I.E.L.D. brought down every last cell," he spat back.
"Hmph. I suppose not everything can grow back forever."
Cap shook his head. "No. You just have to torch it enough while it's down."
They charged toward each other, and Captain America and Red Skull begun their long-delayed battle.