They've done it before - remember the mid 80s show with Valerie harper called Valerie?
I don't remember the specifics, I think it was salary demands so they killed her off rebranded the show Valerie's Family then the Hogan Family - I think the show lasted 4 or 5 seasons without Valerie - The major difference was Valerie was fired after the first season I believe
It'll be much harder to do in season 10 with Roseanne