To expand on
@maccavennie's point
United - The pony tailed Ibramohvic ( sp ? )
Spurs - Kane
Arsenal - Sanchez
City - Aguero
Chelsea - Costa
Liverpool - Coutinho
All of those, bar probably Chelsea, would look weaker without their main man. But, they, like us, would get very good money for their main man, so the trick is spending the money wisely.
Pre the Chinese influence, it would probably be fair to argue that we were more likely to lose Lukaku than any of the above were likely to lose their main man, and that's still the case, but less so.
We need to finish the season well to show we're close to the, so called, big six, which will give us a fighting chance of keeping Lukaku.
If we can do that, and strengthen in the Summer, then there's no reason we can't start to knock on the door of the top four on a regular basis. End of the day, there are only four Champions League places, and, over the next four or five years, I reckon those places will be a bit more fluid than they have been in recent years