I don't think the releases will be simultaneous however I do think that both will be updated sometime next year. The pro is too new for it to go two years, and it will be time for the iPad Air 2 to be updated at sometime next year as well.
So both, yes. When? Well, this is Apple. Who knows?
I disagree about the Mini. They made me wait two years this time from the 2 to the 4 because you can't count the 3 as an upgrade. It wasn't.
Then all 3 of them will be on 2 year cycles. I mean, they make the most money with e iPhone and they will continue to favor it being upgraded yearly.
Just my 2 cents.