According to Comic Book Resources, Arnold Schwarzenegger has only one condition for becoming a member of the Marvel cinematic universe.
In the early days of the Marvel cinematic universe, the studio went out of its way to cast celebrated actors to help bolster the brand's legitimacy. It's easy to forget how big of a deal it was that Anthony Hopkins signed up to play Odin in the first Thor film. Or, if we want to go even further back, how unbelievable it was to read about the original Iron Man cast during pre-production.
Nowadays, Marvel's brand is infinitely bigger than any actor the studio could sign for any role. Where Marvel first sought legitimacy from established Hollywood vets, the studio now propels young actors into an A-list career almost overnight. However, even though Marvel doesn't need to snag big names anymore, the studio is always open to bolstering its ranks with more star power. I mean, The Eternals did nab Angelina Jolie, after all. Who knows, maybe Arnold Schwarzenegger isn't that far out of reach?
In an interview with Men's Health, Schwarzenegger plugged his newly released comedy-drama series, FUBAR, among other things. During his sit down, the actor and former California governor addressed the possibility of doing an MCU film at some point before his extensive Hollywood career ends. Schwarzenneger revealed he's receptive to the idea, but only if one simple yet significant requirement is fulfilled. "If the role is right!" he said.