I agree with you in everything.As you say,
people get tired and fatigue can set in for anything.Next summer is too crowded with super hero movies.Comic book fans will go to see Captain America no matter what,but they are not who account for most of the ticket sales.Non comic book fans in general,families and people who just want to have a good time at the movies,those are who make possible the huge B.O. sales.
Many people will see Captain America trailer and no matter how great it looks and how big the marketing is,
they will say:"That looks great,but another Super Hero movie?,no thanks,I will wait for DVD and go to see something different".Specially when 3 Super Hero comic book movies have opened in little bit more than just one month!!!Thor:May 6,X Men:First Class June 3 and Green Lantern: June 17.