i don't think it will hold up without them either.
i am a HUGE sutton fan, and i really have only gone to see the show as much as i have to see her perform. i think she is fantastic in the part, and it's hard to see anyone taking over that role and really making it work. i can see this being much the same way with maureen.
i just hope that when/if the show closes, sutton moves into something else quickly so that we all have the opportunity to see and hear her!