The “Neon Lights” singer tells On Air with Ryan Seacrest: “I am so excited not only to be one of her bridesmaids, she’s one of my closets friends and it would be an honor to have her on my album. So, I’m trying to figure out which song right now, actually, to put her on. But it will definitely happen.”
Not confirmed as single obviously but anyway if released before the album release I can see it becoming a moderate hit with Demi's power alone. I mean she is capable of have top 20 hits by herself without the need of collabs or PROMO either way so.
Iggy hinted at it long time ago too 
