The Mummy will really test whether strong U.S. showings are really "needed" anymore for these multi-film universes. Even if the movie flops in the U.S., if it does well overseas (and early indications out of Asia seem to suggest it well, at least in that region), that will be all the incentive Universal needs to proceed with their Dark Universe. I don't imagine subsequent DU movies to be big-budget affairs to Universal may just try to manage their monster universe as a low / mid-budget set of films (propped up with high-level acting talent).