Id say XSX shouldnt be more then $20 expensive, if that. 50mm² larger SOC is probably something like that, but Sony is pushing their SOC much harder so I assume ~$20 is best case scenario for Sony, likely its smaller.
Which is to say - they will both be $499.
This could be a good guess.
I just suspect the BOM difference wont be much or any in Sony's favor. The same as their probably wasn't much on One vs PS4 despite the former being markedly weaker.
The things I can really think of being a delta are:
-Soc, Sony's being cheaper.
-Cooling, Sony's presumably more expensive given the clock and Bloomberg article. HOWEVER that said, the Austin Evans video showed a hugeass heatsink for the Series X, and MS may overengineer it similar to how they did One X, so, who knows. We still nominally can charge Sony here maybe, Cerny mentioned super special cooling as well right?
-SSD, I guess Sony's more expensive? I'm not really sure, it's faster, but is that the silicon or the IO hardware?
I mean off the top that's two of three for Sony, not great.
Sony can engineer a "rougher", louder, less refined system and save there though, I think they pretty much did that with PS4Pro and it was probably the right move. This alone could probably make a big difference. We haven't seen PS5, but Series X looks large and refined/costly/quiet, similar to a One X perhaps.
The PRICE may be a different matter, with a slightly weaker GPU Sony may feel pressure to price lower, again, the bloomberg article.