Despite his big mouth, obvious daydreams of playing at a "bigger" club, and occasional absentee effort, he still is our best goalscorer of the past decade by a wide margin. He may not always do the dirty work and act as a complete striker, but he is regularly able to find the net. Believe me, I would love nothing more than for him to stop speaking to journalists every 5 seconds, but I would gladly have him back next year.
*edit*-- Also, if his obvious frustration/desire for bigger things can be morphed into him demanding more from himself and other teammates (not accepting mediocrity), he could be the most powerful player in the dressing room. We'll see. Whether he stays or goes, Lukaku has a lot to demand from himself if he wants to be the world class player that he wants to be.