Sanchez never should have been signed in the first place. Huge waste of money and wages for a position that we didn't need any help with. The only way I would ever say it could be good is if Sanchez played on the right. I would actually like to see him play there. He is way too dependent on his right foot and will have his man beat wide on the left, but then stop to cut back to his right and allow his defender to get goal side of him again. If he plays on the right, he will be able to beat his man wide and either have a shot far post, or put in a cross/pass. If he's not willing to play on the right, then I don't see a point in having him. The problem is who would want him or be able to afford him at those wages.
As for Lukaku, I think he's worth keeping. He's a good player who can rotate in to start some games, and be an option off the bench. Against Liverpool he played on the right and put in a couple of very dangerous crosses. Could be worth having a look at him in that position a little more because we all know he is better at running onto a ball than receiving it with his back to goal.