Come on young man...
No Europe after two years, then you can leave for 50M.
In the meantime he starts every week, earns shedloads, and if he does brilliantly, he gets into the England team and we get into Europe, which means he stays.
Win...
This sort of pragmatism is the only way we will attract the best.
Accept that good players may leave - just ride the wave of their good form like Lukaku, Stones etc. then come out if it quids in.
If we exceed expectations then they can stay.