It remains to be seen how the players progress. While the big 3 have proven themselves in high school, it's not like Butler is a complete unknown. She was one of the better freshmen in the nation on a very consistent basis. She's received high praise from other coaches in the league, and Geno has had a chance to see her play as well. Oh, and Geno had some very positive things to say about her.
Given that neither Samuelson, Collier nor Boykin have played in college (against girls bigger, stronger, and faster), and given that none of them are over 6'3" (Boykin looks to be only about 6'2"), it's an incredibly long stretch to assume any of them would play the 5, never mind play significant minutes there, AND as a freshman no less. Geno NEVER starts freshmen unless there is no one else, or injuries require him to make changes.
Additionally, given that Butler is 6'5", and the year after Stokes graduates, will essentially have 2 years in college, 1 of those practicing with the UCONN team, I find it a huge stretch to say that essentially junior Butler with 2 years college experience would be beaten out by 6'2" freshman Boykin.
Everyone is entitled to their opinion, but that's sort of like saying Stewie should be the backup 2G. Sure she has guard skills, but when you look at the complete picture, it's really really unlikely, and makes even less sense.