What it needs is a return to what it used to be. It succeeds or fails ultimately on having housemates that capture the imagination. But we need to be able to get to know them first.

You've been getting something different every year. What the show needs is a structure and given that they are trying to win viewers back, it makes no sense to completely change the show from what it once was. People coming back will want to settle back into what is familiar. All you do by radically changing the show is alienate what viewers you have left, and make returning viewers just give up on it once and for all.