Yeah the "Lockhart" rumors are getting more and more legit. I am thinking $299, since although the chip itself will be much smaller than XSX (being just a 4TF "RDNA 2" GPU instead of 12TF), it will still need the exact same 1TB of SSD storage setup as the high-end console. The small dip in the CPU clockspeed isn't unexpected and wouldn't have any negative effect on the games. A large part of the CPU's time is draw calls to the GPU - and since games running on "Lockhart" will be 1080p instead of 4K, that means a LOT less draw calls. I'm guessing maybe around 3.50GHz (down from 3.80GHz on XSX)?
At this point, here are my price predictions:
$499 - Xbox Series X, 1TB SSD
$299 - Xbox Series S, 1TB SSD
$499 - PlayStation 5, 825GB SSD
$449 - PlayStation 5 Digital Edition, 825GB SSD