If a GK comes in this window it will again be competition for Migs, not to replace him.
Volland is an incredible right winger who wouldn't need to start every game. he is everything the English media hyped Jordan Ibe and Raheem Sterling to be.
To answer the question as to who he comes in for, in the favoured 4-2-3-1 that we have been playing lately, when fit, it would be Milner.
He is no good as an attacking Mid, and no good leading a line, I agree with that, but he is incredible on the right wing. Have im in a heart beat over Milner, Ibe, Lallana and dare say, Markovic.