Two shows spring to mind: When Karen Mason replaced Glenn Close during her vacation from (the first) Sunset Blvd, the box office fell drastically, and the production's efforts to hide the figures -- to suggest the show is the star -- enraged Close. It became a bit of a thing.
Hello, Dolly! was shrewdly set up with a Broadway star as a replacement -- already playing of the the eight shows -- and if the numbers were lower, the audiences were happy and plentiful and loved Donna Murphy. I would think it's a terrific model for the Jackman absences, still months away. If they brought in, say, Norm Lewis or another theater name, ticket sales would fall but seats would be sold. Finding the Donna Murphy to play Hill may be in the works. But then, in post-pandemic Broadway, all bets are off.
"I'm a comedian, but in my spare time, things bother me." Garry Shandling