I dont see how. The whole team is set up to fashion him with chances. If he leaves we will need a facsimile to avoid the overhaul of the whole way of playing our football. And tbh I think Koeman will be up for that. The way we play right now is not pure Koeman. It's a hybrid between the effort he requires and the particular technical ability of the players he's inherited.
That almost sounds like praise for Koeman, almost.