Users of the large MBP are by and large professionals who need hardware which performs near state of the art levels. The current MBP is a little aged. As discussed many places, anyone in their right mind is at least a little apprehensive about the first iteration of Apple Silicon. A MBP with a processor newly released by Intel, with associated new chip sets, would be a more than incremental step up in known, reliable technology. Professional users of large MBPs could buy now with relative confidence. This would express not so much a lack of confidence, as well informed rational caution.
In the past Apple has often announced new products more or less in sync with product announcements from Intel, with the new product available varying times later. Neither Apple nor Intel want to announce a new product which steals the thunder of the other company's new product, so the announcements are coordinated. Intel has to ship the new parts in volume before Apple can assemble them into its new products.
My guess is Apple will announce a new MBP about the same time as Intel reveals its "interesting surprise" on September 2, with availability to follow somewhat later, maybe the middle of October.
As noted in the MacRumors Buying Guide, right now is a time to be cautions about buying a new MBP.