Either this fall or next spring for sure. And it may be a press release upgrade. Apple definitely has not shied away from that style of unveiling if the update is truly just a spec bump.
We ran into this anxiety last year too. There were actual pictures of the new iPad Pro screen configurations in iOS 12 code (I believe product names too?). They did not show up at the September keynote and people got REALLY worried--myself included, because I had sold my 10.5" Pro to maximize profit. But there was more than enough smoke there to assume that new models were coming very soon.
This year is a LITTLE different because we don't have graphical proof, but that could very well just be because the design isn't really changing too much, if at all.