I really doubt Rosie and Barbara Walters would get along... Barbara likes semi outspoken but controllable and sort of conservative types in my opinion. She loved Meredith and I remember an episode where they had to choose which woman on earth they would marry if they could and Babs chose Meredith. I think none of the other ones chose someone from the show although I can't remember who any of them did choose.
Rosie is too much of a wild card for controlled and controlling Barbara I think. Guest host yes, but I think the show should hire Soledad, get rid of "Star" who only likes to talk about herself (and dissed Kathy Griffin, whose comedy I like) and hire another new person too. I dunno who. But Rosie doesn't fit. (Plus, has Broadway and stuff, doesn't she?).
I could be wrong!