We all know since Disney bought Fox they have the rights to all the mutants in the Marvel universe. And although one theory suggest the coming powers released from the infinity stones snap in Avengers: Infinity War and Avengers: Endgame will unlock mutant powers on MCU earth, the children of the atom may be hear sooner than we think.
It is highly rumored Quicksilver will be appearing in Wandavision. However, many leaks and hints lean towards the Quicksilver from the Fox’s X-Men movie universe popping up instead, or along side the MCU’s Quicksilver. Some even suggest Quicksilver will tell Wanda that mutants are actually common, and her powers are actually a mutation, released by Stucker’s experiments.
This plays well into other theories such as the Hulk and Spider-Man also naturally being mutants, allowing them to survive the radiation.