Doesn't make much sense from Apple's pricing policy on M-series.
MBA 8CPU - 7 GPU 512GB $1,199. ->. 8 CPU-8GPU 512GB. $1,249 so about $50 for a single GPU core.
MBP 14" 8 CPU -> 10 CPU. $200 upgrade ( about $100 per CPU core )
MBP.14" 10 CPU - 14 GPU. -> 10 CPU - 16 GPU . $100 upgrade ( about $50 per GPU core)
So jumping from M1 to M1 Pro entry.
P cores. 4 -> 6. gap of 2 ( at $100/core would be $200 )
GPU core. 8. -> 14. gap of 6. ( at $50/core would be $300 )
Apple is going to offer what they price for $500 for $300? Probably not. It is actually a bigger die ; not just selling "binned out" cores that are actually already there and Apple is going to throw some huge discount at that? I think you doing lots of wishful thinking. Will it be a full $700 jump over the M1. Maybe not. It is a $700 jump from bottom M1 Pro to full Max. The jump to a binned down Max is $500 between M1 Pro and Max. Something closer to $500 might represent a the "between level" discount that Apple is shooting for. $300 is just way too low given what they are charing per cores. Maybe Apple is feeling nice and it is 'only' $400. (about where the Intel model is sitting plus $200. Perhaps a slight discount on loosing two E cores.

. ).
Not going to be a huge SoC discount here because, it is not a relatively high volume SoC. Secondly, when jumping to be binned down M1 Pro die going to be asked to pay for the full die anyway. So again no likely discount. A far more "consistent with Apple" pricing would be to stick with the Apple marked up Intel SoC as a starting point for the M1 Pro, because Apple isn't going to give away "free stuff" on a Pro labeled product.