Assuming we bring in Fekir, I think our midfield 3 will be Fabinho, Keita providing the ball winning and impetus and defensive ability, whilst Fekir is in a more advanced role behind our front 3, free to roam into that space (perhaps even interchange with Firmino when he drops deeper as he often does). Henderson seems the likely deputy for the deepest CM or holding midfield player, whilst both he and Gini can probably deputise in that athletic box-box type player role that Keita will more than likely take. We don't seem to have too much depth in that advanced midfielder/Coutinho role. AOC, though a different type of player, has had a bright start there in his time with us but he could well be out for much of the next season as we don't have a timeline for his recovery. Milner who had a very good Champions League, provides a bit of versatility and is a cool, calm leader who has plenty of experience about him.
I don't know where the likes of Lallana, Grujic or Woodburn really fit in. to be honest they don't really have one strong position, or in the case of the latter 2 probably haven't had enough opportunities to see where they really contribute to the team. Lallana seems to be a Klopp favourite and I suspect he'll be shoehorned to be that advanced CM while the new signings settle into the pace of the team and league, and while AOC is still recovering/rehabilitating. I don't think he quite has the pace or explosiveness to play effectively in the front 3. to be honest to me that looks like quite good selection for 3 midfield roles : Keita, Fabinho, Fekir, Hendo, Gini, Lallana, Milner and AOC. There is plenty of talent, athleticism, leadership there. We've got players that can do the legwork as well as some options that can carry the ball and be good in tight spaces, as well as players that distribute well. Within that bunch I think there is probably some goal threat too. There is a good level of versatility and freshness there. I don't think we will miss Emre Can at all.