Yeah Markovic is ideal for covering both wings. Perhaps a starter if he steps it up while out on loan.
Markovic Firmino Coutinho
-------------Sturridge------------
Benteke is going to be a weird one with Klopp's preferred formation. Lallana is worth keeping because he can cover pretty much anywhere from CM to AM/Winger if need be, although I wouldn't be against selling him should a £15m+ offer come in. Ings we should definitely keep, as he's a pretty damn good third choice striker (better than what the other clubs have).
Milner is a weird one.
With the current squad, we have far too many players wanting to play up top. If Lallana wants to stay, he needs to produce chances and be creative from the middle, instead of going for the net. I don't know how good he is at central midfield, but I'd rather Can and Henderson there instead.
I saw earlier someone had the idea of having Sturridge on the wing or behind Benteke, he would hate that. Studge does great with a partner, but not by being a winger or striking from behind. One of the reasons he left Chelsea was because he wasn't getting the opportunity to play up front and they kept shoving him out wide.
Coutinho needs to play centrally, which makes the purchase of Firmino really weird. To get the best out of both, they need to play closely together and both play best in a central position. Markovic and Ibe are the only out and out wingers that we have, and Ibe is certainly not an end product, while Markovic is on loan due to Rodgers incompetence.
Klopp will have to figure it out. Either play with two strikers or shuffles the positions around. He could always pull a Real Madrid where despite Ronaldo starting LW, as he advances, Benzema drops back as support. Benteke could always do that with Sturridge. I hope to see some flair and difference by Christmas hopefully.
Best wishes.