I always worry a bit about my favorite performers, including Yehaa Bob and the Citizens of Hollywood. The one thing that's different about Yehaa Bob is that he consistently *PACKS* the River Roost Lounge and most everyone there is buying drinks, snacks, etc. I've walked by the River Roost Lounge on one of Bob's nights off and it's relatively dead in there. If Bob were to go away completely, Disney would be losing out on that $$$ coming to see Bob. Sure, there'd always be someone going in to get a drink or two, but it wouldn't be nearly as full as it is Thurs-Sat nights.
As much as I like Banjo Brothers and Citizens of Hollywood, I can't find the same reasoning for keeping them around. I can think of other reasons to keep them, but none that are directly related to $$$.