If the rumours are true that hes had talks with Tuchel, looking for a house in Paris etc then I think we're probably at the point of needing to negotiate the sale. Going to PSG for him would be absolutely amazing and something he warrants for years of dedication. Yes, he will be a loss for us (but not irreplaceable), but you'd have to ask where his head would be after the transfer window closes if this does fall through.
I get that hes under contract, but hes not and Evertonian, hes given his all for us and any of us in that position would want the same.