Personally, I always dismiss any argument that's based on "does or does not make sense" - mostly because we see the patterns that we want to see and it's not necessarily what Apple's marketing or strategic plan is (though I'm also learning not to ever say "Apple will or will not do ________").
The long and the short of it is that the iPhone and OS software is about the only thing we can ever reliably say will release on a regular schedule. It's pretty obvious we're going to see new iPads. Will there be new Pros? There's a lot of conflicting data, but I'm guessing not unless there's a good reason to.
Having said that, the upcoming release could be very telling about Apple's future iPad strategy. Their latest release was the Air 3 and the Mini 5 back in the spring. What is going to be the distinguishing factor between the new "iPad" and "iPad Air" products? Maybe it would be a good idea to update two sets of iPad products at a time (iPad/iPad Pro, and Air/Mini).
An argument against new iPad Pros (at least in relation to release of iPad OS) is that iPad OS will be released around the iPhone event. The only reason to show a new iPad at the iPhone event is if there isn't a compelling update to the iPhone / Watch. Also, a consumer iPad with iPadOS might be a better shot to target the masses instead of putting a focus on the Pro.
At the end of the day, if you're in the market for a new Pro buying advice is the same as always: Get what you need when you need/want it. Even if there are new Pros, I doubt the upgrade would be significant at this point where it's going to last that much longer than the 2018 models.