Lukaku is an excellent player but he have one BIG problem and is the drama he made in every team he goes, is incredible but he has something in his brain that make him feel uncomfortable or wants to leave, you can see it when he was in Chelsea and other teams, so he can have so much troubles in Saudi arabia i guess.
Lukaku is a good player, but he struggles to choose a club that suits him, changing clubs but he can't seem to show his best. I don't know if this is because he is very difficult to adapt, or if the club he has been playing for does not have a style of play that suits him.
If he chooses an Arab club to harbor him next I'm also not too sure if he will be able to show his best game or not. He's 30 years old now, his experience should have made him adapt to the club more quickly, but so far I've seen him unable to do so. As for the intensity of the competition, the SPL may not be like the Premier League and Serie A, maybe that will help him to show his best performance which is very difficult for him to get.