You are talking as if there no room for improvement on PS4 as well.
Saying the xbo has "more room to improve" implies the ps4 will also improve of course, I don't know how you read the opposite. I'm just saying the curve for xbo will steeper early on as devs learn the xbo and it's more unique architecture better. The ease of development the ps4 enjoys also means they are able to utilize the available power easier now.