(Image credit: Marvel)

Ever since Marvel shook the world by announcing Robert Downey Jr.’s return as Doctor Doom, I haven't been able to stop thinking about what’s next for the MCU. As we edge closer to December, the hype surrounding “Avengers: Doomsday” has reached a fever pitch (and we haven’t even got the trailer yet). It’s easily shaping up to be one of the biggest, most monumental film events of the year.Honestly, my group chats are constantly flooded with speculation, since my friends and I love to talk about everything Marvel. How will the Multiverse sustain this terrifying new threat? Is this Victor von Doom a corrupted Tony Stark variant, or someone completely fresh? The theories are flying fast, and that’s half the fun of being a fan.If you're as excited as I am for this upcoming movie, here are five of the most convincing “Avengers: Doomsday” fan theories and what they could mean for the MCU.1. Doctor Doom uses Tony Stark’s body to save (and control) Earth-616

(Image credit: Alamy)This first theory is quite interesting when it comes to Doctor Doom’s true motive. It actually suggests that he isn't simply a version of Tony Stark from another universe. Instead, after Tony's death in “Endgame,” Doom takes over Stark's body in an attempt to keep Earth-616 from collapsing.The idea comes from the Anchor Being concept introduced in “Deadpool & Wolverine,” which says that every universe relies on one key person to hold it together. Since Tony was Earth-616's Anchor Being, his death could be causing reality to slowly break apart.According to the theory, Doom uses a mix of science and magic to hijack Tony’s corpse and transfer his own mind into it (a bit strange, I know). This would explain why Doom looks like Tony Stark while still being a completely different character. If true, it would create a huge emotional dilemma for the Avengers since characters like Spider-Man would see the face of their fallen friend and mentor, making it much harder to fight Doom even if they know he's the villain.2. Doctor Doom is a fallen Tony Stark on a multiversal revenge mission