I still don't understand why this movie isn't be released at Christmas. Looking at the release schedule at BoxOfficeMojo there is little competition for big budget action movies during the holidays of 2018...at least no more than previous years. This spring/summer over the course of 8 weeks we are going to have The Avengers: Infinity Wars, Han Solo Story, Deadpool 2 and Jurassic World 2. I think there is a good chance of significant cannibalization among these movies as the high grosses anticipated for each depends on multiple viewings. That is less likely to happen with these big blockbusters opening so close together. Infinity Wars is the least likely to be effected as it is first out of the gate and has 3 whole weekends to itself.
Even if this Star Wars movie is of reasonable quality along the lines of Rogue Squadron, I think it will have a tough time cracking $500 million domestically and $900 million worldwide. Releasing a week or 2 before Christmas as has been the tradition the previous 3 years might have resulted in a few hundred million more internationally.
2018 Holiday release schedule notable films
Nov 9th
The Grinch (Animated)
Nov 16th
Fantastic Beasts: The Crimes of Grindelwald
Nov 21st
Creed II
Ralph Breaks the Internet: Wreck-It Ralph 2
Dec 14th
Spider-Man: Into the Spider-Verse (Animated)
Mortal Engines
Dec 21st
Aquaman
Bumblebee
Alita: Battle Angel
Dec 25th
Mary Poppins Returns
Actually a lot of big budget films with action Alita and Mortal Engines they would have to deal with along with a heavy dose of family films that will have legs carrying them well thru holiday's and then a movie like Aquaman which will be competing for some of the same market as SW
So overall dropping this on Christmas this year would maybe not be best option given the crowded field
And studios are not keen in having January as month of most exposure for movie as it is generally a slow month and can be effected by weather in parts of US as well as having the negative of kids being back in school
So when looking at that crowded field it isn't safest bet to drop a film like Solo there