If I was someone close to Lukaku I'd be in his ear telling him he is still really young for a footballer, continue his development, etc then either move on or Everton are there. I'd be reminding him that his hero, Didier Drogba, didn't join Chelsea until he was 26, and won his first trophy at 27.
Lukaku has the physical prowess to be at the high level for longer than most players and has got plenty of time to achieve big things.
I think young players, and to be honest, the younger generation want things instantly, when it is sometimes important to be paitent. I love him, easily our best player, but I still think there's parts of his game missing and he is not an upgrade on any of the top top teams current strikers. I'm talking Lewandoswki, Ronaldo, Suarez, even Costa Aguero. The one that worries me is United, but I still think they'll go in for Griezmann and keep Zlatan.
I'm not resigned to losing him just yet.