Just thinking ...
Imagine they kept the defence the same next season. First off, they'll definitely buy a new starting keeper, but think about the back 4. Baines is about 33, Williams will be 33, they'll get another season out of Jagielka who is about 35ish. Coleman could quite possibly be fucked as well, he himself is not far off 30.
When Lukaku is off they'll need at least 2 strikers, one to replace him in the 11 and another one to sit on the bench (Wazza?) - Think most people would put their lives on them not finding a 25 goals striker for next season.
The midfield is about as strong as it gets for them and it's still bang average.
They also have European footy to worry about.
I think they'll finish about 12th. Would like to think they could get dragged into something though ...