I think Epic Universe will definitely be competition for boys. Even at preschool age, all the little guys in my area were dressed up as Mario this year. And it likely doesn’t help that Magic Kingdom has really gone all-in on princess culture. It’s probably helped them to absolutely corner that market, but with Cinderella’s Royal Table, BBB, Sir Mickey’s, and a fair number of princess themed attractions… there seems to be a lot that is girl themed but not much that is boy themed.
It seems like Disney has had a hard time coming up with new IP that really resonates with boys, for whatever reason. Mickey is still a hit, and Spidey, but when it comes to original content from the past decade or so.