I thought about this some time ago starting lineup doesn't need to change that much. Midfield is the area that needs to be rebuilt. Goalkeeper might be, depending on how Howard does but Coleman - Stones - Jagielka - Baines doesn't need to be changed at the start of the season. Alcaraz and Distin need to be replaced, which means one new player from outside and hopefully the youngsters can fill the other position. In attack Lukaku will still be the main player (unless his agent gets him a move). A second-choice striker would be nice, though.
But in midfield I can only see three players with long-term future: McCarthy, Besic and Barkley. This means Bobby needs to find at least two wingers and most importantly a playmaker. So, to recap our lineup in the first match of next season could be
Howard
Coleman - Stones - Jagielka - Baines
Lennon - McCarthy - "Rafa Silva" - "Andre Ayew"
Barkley
Lukaku
Subs: Robles, Garbutt, Oviedo, McGeady, "Claudio Beauvue", "Stefan Reinartz", "Gerard Deulofeu" (loan).
Those names are just picked from the rumours section to show what kind of players I'm thinking about.