Scott Lang's Ant-Man lends himself to fan theories more than almost any other MCU character. With his ability to shrink down to microscopic sizes and explore the inner workings of universes much smaller than our own, the doors for unsolved Ant-Man mysteries are wide open. It's no wonder fans were able to catch so many Ant-Man Easter eggs, given that the shrinking premise is designed to hide things in plain sight.
As long as the Marvel Cinematic Universe gears keep turning, so will the Ant-Man fan theories. All those unanswered questions from Ant-Man have been thoroughly explored - leading up to hardcore conspiracies and suspicions about the plot of Ant-Man and the Wasp.
The ability to enter a realm where space and time become irrelevant leaves holes in more than just math and physics. Fan theories about Ant-Man and the Wasp attempt to fill those holes with explanations, and make sense of a vast and astounding world full of Marvel mysteries.
Ant-Man Will Be Needed To Fight Against Thanos
Ant-Man's utility in the MCU goes far beyond the ability to shrink down to super small size. According to Redditor BassAndBass, he will play a huge part in the fight against Thanos. It all comes down to sequencing the timeline of the MCU films, since Ant-Man and the Wasp comes out between Infinity War and its sequel. Presumably, Thanos will not be defeated in the first installment.
If Thanos acquires the full Infinity Gauntlet and can control the entire universe, the only way to beat him would be by stepping outside of the tangible realm. Ant-Man's knowledge of the Quantum Realm might help the Avengers take Thanos down.
The Movie Involves A Search And Rescue Mission Within The Quantum Realm
The long-since-gone former Wasp has not been abandoned in space and time. Fans have speculated that Janet, the wife of Henry Pym and mother of Hope van Dyne, will be reappearing in Ant-Man and the Wasp. According to Evangeline Lily, who plays Hope,
In Ant-Man and the Wasp, they are trying everything in their power to safely enter the Quantum Realm and return back from it because they have evidence from the first film that Scott Lang was able to do that.
During their mission, it's entirely possible they'll look to save Janet and gain a greater understanding of the Quantum Realm.
The Villain Will Not Be The Wasp - It Will Be Ghost
While the identity of the true villain in Ant-Man and the Wasp remains shrouded in mystery, many have deduced it's not the Wasp at all; the main battle will be against Ghost. Instead of the Wasp as the main antagonist, Ghost will be the one wreaking havoc. As opposed to the comics, Ghost will be played by a woman.
The Wasp Joins Alongside Ant-Man - Much Like War Machine Joined Iron Man
Comparing the Ant-Man to Iron Man, Redditor 32_Bit_Bandit speculates Ant-Man and the Wasp will follow in its footsteps. This fan theory would not make the Wasp the villain, but the sidekick. In Iron Man 2, War Machine joined alongside Iron Man, and, according to this fan theory, the Wasp will do the same. Going against the popular Marvel movie theme of adding the man antagonist's name to the title, Ant-Man and the Wasp hints at the possible pairing of the two as allies.