I followed Detective Comics because Tynion added Tim Drake to the roster. I know Tim was a focal point in the entire storyline throughout that series, and received a open ended send off, implying that he was going to take his time out of Bruce's shadow. As far as I am aware there are no official announcements on what is next for him.
Every writer is welcome to use which characters they feel they can use to tell the story they want to tell (Eg. Tynion liked Drake and so included him; King is interested in mainly Bruce and Selina, with some allowances for Nightwing and Superman). However, it seems distinctively weird that Tim wasn't mentioned at all as pertains to Batman - Catwoman wedding. I get that there was a Joker throughline in the Prelude series. Suicide Squad movie has raised Harley's profile, and the connection with Joker is valid, but the fact that Harley Quinn bumped Tim from having an issue was odd. Jason Todd was included (even though he is kind of the black sheep of the batfamily) while Tim was not.
However, from a business standpoint, does Tim Drake not sell comics? I liked the Red Robin run pre-flashpoint (but don't know what the sales numbers for that was). Post flash point, Teen Titans was a horrible trainwreck and didn't sell very well. After that, he was essentially sidelined until Detective Comics.
I don't want this to turn into bashing other characters, but from a sales numbers standpoint, are Jason Todd (Red Hood and outlaws), Dick Grayson (Grayson, Nightwing), or Damian Wayne (Robin, teen titans, Super Sons) comic book sales numbers better than Tim's? Comparing the Teen Titans sales number is probably the best comparison, aside from quality. (The impetus for this post was the news that Super Sons is canceled, but that is likely due to Bendis and his direction on Superman, although I don't know how well that series sold)