I'd be surprised if Lallana wasn't first choice in midfield this season given his off-the-ball qualities. He's like a merger of Allen and Coutinho which is perfect for our style. Of course "first choice" is a term that applies less and less in modern football, but in weeks when we only have one game against a decent opponent I'd wager that he'd be picked more often than not.
Its fantastic to have the option of whether to play Coutinho or Lallana though. I think opposition managers are going to have a tough time predicting who we'll play and which formation to prepare for defensively given the multitude of options available.
I wouldn't be surprised to see Can-Henderson in away games though, with Sterling-Sturridge-Markovic ahead of them cutting teams apart on the counter. Its gonna be good with so many options!
Formation is an interesting one; I think our current options in the squad lend themselves to being able to play a lot of different shapes. In my opinion, Allen, Henderson, Can and Coutinho all best suit playing in the no.8 position. Looking at that, 4-3-3 would suit us. And yet you have Lallana, whose best position is probably as a no.10, Sterling, who I think really works well as a no.10 and Markovic, who I think will most fulfill his potential by permanently becoming a no.10 in the future, as well Coutinho and Henderson who have both played well as no.10s before. That would point away from a 4-3-3 and maybe towards a 4-2-3-1
It's going to be really interesting to see what Rodgers does with that. I wouldn't like to predict which one he will generally prefer to go with this season (of course, the fact we have plenty of options to play a 4-3-3 and a 4-2-3-1 brings in the diamond midfield as an option as well, where you play four midfielders). I do think we'll see a similar flexibility to last season though.