WARNING: The following contains spoilers for Avengers Forever #3, now on sale from Marvel Comics
The Avengers have found themselves up against some of their most powerful enemies recently, confronting variants of the Masters of Evil who've gained impossible amounts of power in their respective realities. In some cases, they've even become the idealized version of the core-universe antagonists, including expanding upon one of Marvel's most vile villain's ultimate missions.
Avengers Forever #3 (by Jason Aaron, Aaron Kuder, Cam Smith, Scott Hanna, Guru-eFX, and VC's Cory Petit) introduced an apparent multiversal Council of Red Skulls, showcasing how Hydra had risen to become a multiversal threat -- exactly the kind of dream come true for the Earth-616 and Marvel Cinematic Universe versions of the villain.
Avengers Forever has been largely centered on Robbie Reyes, who's been trapped on the brutal Earth-818. The rest of the multiversal Masters of Evil have pressed their attack against the Avengers of Earth-616, but Ghost Rider has ended up in the grasp of Black Skull. A variant of the Red Skull, Black Skull has gained control of his world's entire symbiote population and used it to instill a terrifying Hydra-dominated world order. In effect, this is a reality where Captain America's ultimate enemy has won, and broken reality to his will. But while he's proven to be incredibly powerful, he's not indestructible -- with Ghost Rider eventually breaking free of his chains and taking control of the symbiotes with his apparent role as the All-Rider.
But despite this, Black Skull was revealed to have a major secret weapon: while exploring Black Skull's base in search of their allies, the Vision and Moon Knight of this reality stumble upon a series of multiversal gates. Even with the Black Skull defeated, there are numerous other variants of the villain who are part of an alliance of Skulls. They even directly reference their shared place within Hydra by noting that if "one Skull falls... a thousand more shall take his place." It seems that the Multiversal Masters of Evil have an entire Council of Red Skulls at their back, each possessing their own dark attributes (and multiple with their own symbiotes). It's a dream come true for the Red Skull, who has always wanted to spread the power and influence of Hydra across multiple globes.
It seems he eventually ventured off into entire alternate dimensions, recruiting an entire army of variants to help him truly create a potentially endless reich that could try to spread across all of creation -- a Hydra that knows no end. On top of having his own reality to control, Red Skull has seemingly begun the process of spreading his power across different dimensions -- similar to the mission of the (doomed) Red Skull from the first episode of the MCU What If...? series. It seems that while the Earth-616 and MCU variants of the Red Skull haven't achieved the attention of this apparent alliance, their dreams of a united Hydra front do come true in some form.
Entire realities are likely under the control of the Red Skull, which gives the villains a major edge in any upcoming conflict for the fate of the Multiverse. Their apparent leader also bonded with a symbiote, wears the banner of Hydra on his chest -- suggesting this is truly the ultimate evolution of the villainous organization and Red Skull's plans. With the heroes of countless Marvel realities being seemingly drawn into the mystery of Avenger-Prime, there's a question as to whether the heroes can overcome such a wife-ranging and brutal threat. But with Captain America a major figure in the current Avengers, it wouldn't be surprising to see him take personal offense to the spread of his greatest ideological enemy across other universes.