The cast needs an overhaul. Whichever person they cast next to 'shake up' the show will be iced out like Denise was and like Sutton basically is currently.
I really think that ideally the solution would be to fire either Rinna or Erika, regardless of my (very negative) opinion of them, the biggest issue is out of the four force flop whatever, they are the ones most responsible of the dynamics getting stale, Dorit has shown that she is able to play both sides of the fence (see the Denise situation), also out of the four them she's the one that pulls less gravitas if you get what I mean, and Kim's sister is not going anywhere soon.
Having the Fox force flop reduced to a trio would be ideal in my opinion to turn the dynamics less stale.
I am quite convinced that Erika will get the boot after this season, whereas Rinna, even though she is literally gone absolutely batshit online I think she'll be safe.
Diana Jenkins at this point has to be a one and done housewife, the reception online has been overwhelmingly negative towards her.