Here's a good site about RAM prices for the last couple of years/decades, it seems to go up/down a lot.
So whatever is happening at the moment doesn't necessarly reflects what it will be by 2020-ish.
https://jcmit.net/memoryprice.htm
I could see Sony going for 24GB of GDDR6 with a 18/6 split, that still runs it on a 384-bit bus.
CPU is predictable at 3.0GHz and 3.2GHz being the max if it's a 8/16 setup (Zen2 with some feats from Zen3).
Navi GPU with maybe some feats from the GPU that comes after that, but this I doubt case for me due to AMD's GPU side of the business as a whole.
The 7nm process will be mature by then and the rest is already available so they are good there, Sony will get a nice push in terms of bandwidth if they go with Samsung again.
Both companies know what lies ahead, I think it comes down to who is going to pull the trigger first and strangely enough I think MS might be the one.
EDIT: the slide sites are claiming to be true is from Twitter, it's the same one that Sony? used for PS4 "Neo" / Pro just edited to make believe.