I wouldn't be surprised if they do go with LLA with a duet with Hunter but it is way early for them to announce the 5th single with SYA just reaching the penthouse. Usually we don't know the next single until the current one goes recurrent.
I would think they would space the singles out just a bit so there won't be such a huge gap between the last single and the lead single of her next album
Four up/mid-tempos in a row was enough, please release a ballad. It's obvious Wine After Whiskey was not only a fan favourite, but a favourite from several critics. It's clearly the best move right now to release!
he's the male version of TS tbh 
