Yes and no, I don't think the majority are the SW fandom, but it's myopic to think they're not going to have an impact because casual moviegoers outnumber them. In investment terms, the SW fandom is the equivalent of Blue Chips investments - the safe core of your investment portfolio; yes you want to attract other audiences, but it's foolish to alienate that audience, because in the days of social media, they are just as crucial a part of generating hype as everyone else. Remove that hype or worse, generate a negative buzz around it, and that is something which the casual moviegoer is going to pick up on.
Only if you ignore the impact fans will have on the buzz around a movie in this social media age.
Again though, alienating fans is going to affect the buzz surrounding the movie, so you can't realistically look at this in a vacuum.
I completely agree that the casual movie-goer simply wants to have a good time and see an enjoyable movie and aren't going to get hung up on canon. However they are going to be swayed by whether the buzz around a particular Star Wars movie is good or bad and base their decision to watch it on that to a reasonable extent. The thing is that it's the fans who will pay that much attention and do care about things like respect for canon, who are going to create that buzz- either good or bad.
Remember, the most effective form of advertising is word-of-mouth.
That doesn't hold true though. If the hype were there, then people would be turning up in droves - even if it was 6 months apart; Black Panther's proximity to Infinity War is a textbook example of this. The fact is that TLJ was divisive and had mixed reviews, while Disney alienated the fandom rather than reaching out to them, whereby they would have generated hype about Solo. That didn't happen, so what marketing that was done, wasn't supported or hyped up anywhere near as much as it could have been. The end result was a killed-off buzz around this movie - hence a feeling of fatigue among general moviegoers.
And no, that's not saying that casual movie-goers don't matter compared to fans; rather it is saying that with established franchises, while casual movie-goers get swept up in and ride the wave created by the hype, it is the fandom which is the group which is instrumental in creating that wave to begin with. Without that wave, there's simply nothing for casual movie-goers to get swept up in to begin with.
Howso? How are the two not trying to build a massive cinematic universe with a tapestry of stand-alone and event movies which both appeal to the fandom and generate and maintain wider audience appeal?
You're comparing apples and oranges here though. SW fans were introduced to the property through the original films and then the prequels so for them, it's very much centred around the films. The same cannot be said for Bayformers, where you really do need to draw a distinction between the transfandom and bayformerfandom, where there will in some cases, be some overlap. The reaction from the transfandom wont do much to to kill a Bayformer movie (though I hear fire helps ), but, if you start talking about say, the Bayformerfandom, such as with ROTF in the case of Western Markets and TLK in China, then it's a very different story.
I find it interesting how everyone was saying that before this movie came out - right down to the fact that Solo would be a success, the boycott would achieve nothing and Disney wouldn't feel it if it did happen. Yet the complete opposite has happened. While I'm sure many people in Disney and who are viewing these new movies as vehicles for Cultural Marxism, would love it if fans did suddenly become silent and compliant, it's not going to be happened and it's a factor you ignore at your peril as Lucasfilm.