I'd say that if they offer 15 million plus add ons based on his performances, potential senior England call-up and percentage of any sell on value then we should start to listen.
As previous posters have said, the Trees going up could do us a good favour financially as it means another club now with the means to pay handsomely who are hugely interested. As we know there's a "gentleman's agreement" honoured for the playoff final that sees the losing side bag the gate receipts etc to the tune of maybe 3 million, it would be nice if we got that kind of gravy added to the Spence fee just for NF getting promoted.