Do you really believe that they would close the show if Stritch chose not to extend, even if Bernadette was willing to? That sounds a bit like putting the cart before the horse to me.
I think Stritch has said that her decision will rest on her health and stamina, rather than how much fun she's having. She's obviously in great shape, but eight shows a week for six months can still be exhausting.
"You travel alone because other people are only there to remind you how much that hook hurts that we all bit down on. Wait for that one day we can bite free and get back out there in space where we belong, sail back over water, over skies, into space, the hook finally out of our mouths and we wander back out there in space spawning to other planets never to return hurrah to earth and we'll look back and can't even see these lives here anymore. Only the taste of blood to remind us we ever existed. The earth is small. We're gone. We're dead. We're safe."
-John Guare, Landscape of the Body