Based on the story that WandaVision ultimately told, the use of Taylor-Johnson’s Quicksilver would’ve dramatically changed the series. Wanda initially hesitated to believe that “fake Pietro” was her brother and created a sense of mistrust throughout the show. This would not have happened if she recognized him right away. It also would change the Ralph Bohner reveal, which fans might’ve preferred in this case, as someone who looks exactly like Quicksilver living in Westview would be a tad unbelievable. That said, it is easy to imagine Quicksilver having a larger role in the series and the finale if it was Taylor-Johnson’s version. He would have been another family member that Wanda would have had to say goodbye to as the Hex collapsed. Instead, “fake Pietro” has a rather ambiguous ending to his story.
Since Taylor-Johnson didn’t return as Quicksilver in WandaVision, it is unclear if he’ll ever play the character again in the MCU. There is a chance that Quicksilver could secretly be part of Doctor Strange in the Multiverse of Madness. Scarlet Witch is confirmed to have a big role in the movie, and the Multiverse aspect could provide a path for another version of Quicksilver played by Taylor-Johnson to join the MCU. Only time will tell whether or not the MCU’s Pietro will be back.
Originally from https://screenrant.com/wandavision-quicksilver-aaron-taylor-johnson-return-considered/