Not sure she'll ever reveal the asshole to be honest. I mean she's teasing and withholding it for everything it's worth right now, she surely must know that that's what a lot of her subs actually want to see. Knowing the way she operates she might do the full reveal at Christmas/end of year.
Guessing next step would be a thong with some showing, or covering with a finger. Either way, she'll milk this for all it's worth as realistically the only 2 remaining plays she has left are open pussy and asshole.