I'd been planning to replace my 2018 15" with an AS 16" when they came out, but I was banking on it being some time next year. If it really does get announced tomorrow it's going to be a much harder call, especially after just getting an iMac and new phone.
Based on the single-core performance of the A14 if the A14X (or whatever) has 8 performance cores the CPU performance would easily outpace any currently-available Intel laptop chips, but the GPU is the real question for the 16". You expect an integrated GPU in the 13" or Air, so my assumption had been Apple was going to wait, for whatever reason, before tossing out Macs with a beefier GPU.
Assuming Apple doesn't decide to downplay GPU performance for the first gen, I don't see the A14-whatever's GPU cores being able to meet or exceed a 5300M with 4GB GDDR, much less a 5600M with 8GB HBM2, so that would mean a 3rd party GPU is a must.
One thing I don't get is all the bemoaning no update to the form factor. The iMac, sure--the ultimate evolution of the iMac's shape would be to lose the chin and become a giant iPad on a stand. But what are you even going to change on the MBP at this point?
I mean, seriously, there hasn't been any substantial change to the form factor since the Aluminum PowerBook G4 released in January 2003. It got thinner over time, the corners got a little rounder at some point, the bezel on the screen got blacker and smaller to allow a bigger screen in the same footprint, the trackpad expanded to fill all available space, a Touch Bar appeared, and the contours of the case changed slightly, but fundamentally it's the same industrial design now as 17 years ago, just refined to take advantage of technological improvements.
With a full OLED screen, and maybe a hole-punch camera or notch, you could make the screen a bit larger or the footprint a bit smaller, but only slightly. The hinge design hasn't warranted a revamp in nearly 2 decades, what are you going to do with it now? I guess you could square off the edges of the case like a current-model iPhone or iPad Air/pro, but given what it feels like in the hand now I'm not entirely certain I'd prefer that. Basically, though, I could imagine no more than subtle refinements in the form factor for the foreseeable future.
The only exception I can think of would be if the entire thing was re-envisioned to work like a Magic Keyboard for the iPad... which might be awesome or might be a step back. The way I use my laptop 95% of the time (on my literal lap on the couch) that would definitely be worse than the current design.