I reckon a base MBP 16" would go for $2'999, with a quad-core i5, 8GB of RAM, and 256GB SSD, and I wouldn't be surprised if a top-spec model with i9, 32GB, 2TB and Vega 20 topped $6'000.
That's probably about right, considering their overall pricing direction. It seems a little ridiculous though. As others have pointed out, 16" is likely to be a bezel change. I would have to check an existing one. If it's several tenths of an inch above 15", then they may be able to push it to 16" without a lot of changes. I also don't expect footprint to really increase, because that tends to go against their mantra.