Keep in mind, Blade Runner 2049 was considered a box office bomb, with general audiences not seeing it in droves either. When in reality, it was one of the best movies of the year. I'm not going so far as to say Solo is as good as BR2049. But I think there is a similar thing going on here, given that Solo is in fact a good movie, and yet people are considering it to be a bomb. The time of year thing is a big factor as well. Not so much that SW movies can't ever work again at this time of year, just that the change was so sudden and abrupt, going from three consecutive December releases to a sudden May release. I don't think general audiences were ready for that. In addition to Solo being released alongside the other major blockbusters mentioned. As far as SW fans go, it won't have any impact on Celebration and I would still expect the cast to appear.