This means Rossmo is finished on Harley Quinn. In fact he is not scheduled for any of the 5 Harley Quinn books scheduled for August, nor even any of the countless covers (5 books with variants).
The HQ Annual solicit says
Tune in for the final installment of Harley Quinn’s Task Force XX Space Extravaganza, plus the start of a new status quo for Harley Quinn!
It's like they decided to burn off the entire final Stephanie Phillips story in August. So maybe showing no real confidence, rather than what looked like a lot of confidence, in this run of the character.
I would hope for a completely new creative team. Replacing Rossmo is start, and I would also like to see someone else have a chance to write in place of Stephanie Phillips.
Wondering what Harley Quinn fans think, but I didn't spot a general Appreciation thread for her.
That said, Rossmo does seem like an unusual choice for a book about Tim Drake. But you could say that about anything Rossmo works on. He's polarizing. His fans like him, but no one seems to be entirely neutral about his style.
There will be a lot of people who will dislike the Tim Drake book entirely because of the art.