Considering chip shortages and the fact that most iPads but especially the (M1) iPads Pro are so incredibly fast and ahead of the competition, I wouldn't be too surprised if Apple pulls an "Apple Watch 7" on the entire iPad line-up and just give them some minor bumps in specs or aesthetics, like different color options and slightly improved displays, more internal storage, more RAM, etc., while keeping the M1 chips for the iPads Pro and maybe just getting the iPad up to A14 and the iPads Air to A15.
Or, perhaps even more likely, they'll just stall on new iterations until late 22 or early 23.
iPads are still selling amazingly well and are sold out in many regions. There's hardly any need for Apple to add to the lineup right now.
I'd get an M1 Pro now and not worry about the next model.
And as apps like Final Cut, Logic, etc., may not ever get ported to iPads, the current iPads Pro are way over powered for the apps they support.