Isnt the 10core CPU like 1800 USD/EUROs? Not sure about price of that Xeon, but i think i7 6950x is, from what i could remember... and you would want to spend that much money just cause of Ashes? In situation, when already 4,5GHz 5820k gotta run the game flawlessly?
Now if i had the money, i would probably want to buy it myself, even if i did not need it, cause i am standard nerd enthusiastic about the latest and most powerful hardware, so i can definitely understand... but in that case there is no need for any other justification...like whether some game will perform even better, when it already runs like a charm and you would not notice any difference anyway...
EDIT: If you want to improve your experience, i think GPU upgrade would be far more sensible choice. 5820k at those clocks is already plenty fast IMO, but you could do way better than 390x. Like 1080 SLI or Titan X....