Back in 2015, Avengers Age of Ultron saw Scarlet Witch inflict a nightmare on Tony Stark.
In the vision Iron Man came across his fellow Avengers dead on a battlefield, with Captain America breathing his last few breaths.
Some Marvel fans are wondering if this is a precursor to the original team – who all survived the Snap in Infinity War – dying in Avengers 4.
The theory was brought up at ACE Comic Con over the weekend where Scarlet Witch actress Olsen gave her answer.
She said: “I don’t know. I don’t know if that’s what could have happened if Ultron took over.
“I’m not sure. I think it’s up to interpretation.
“It wasn’t something that I remember someone was saying that we’re going to go full circle to Infinity War — there wasn’t an Infinity War at that time [laughs].
“But I think I always thought of it being what would happen if Ultron won.”
She added: “But I think it’s more interesting the way you’re thinking about it.”
Nevertheless, her co-star Hiddleston said: “Well, maybe Tony has got the long view.”
During the panel, Hiddleston also addressed if Loki was really dead.
He said: “Listen… I’ve heard some amazing theories about this.”
He added: “I was in a park in London a couple of weeks ago, and some guys came and said hi, and they asked me the same question.
“They said, ‘Hey, listen, we need an answer to this question. All the other times Loki’s died’ — there’s been a few — ‘he stabs with his right hand. And now he’s stabbing with his left hand.’
“I was like, ‘That’s incredible attention to detail.’ Your guess is as good as mine.”
Avengers 4 will be released in UK cinemas on April 26, 2019.