It's simple for me - if we can/do get an upgrade as a regular starter, keep him in the squad for rotation and cover. Why do some folks seem to think it has to be one-in one-out? You do that when the incumbent is rubbish, not when he's a very good player who can contribute a lot to the team.
If / When the team has the likes of Skrtel, Flanagan, Henderson, Milner, Lallana, Ings, etc. for rotation and cover, we know we're back to being a regular top four team and title challenger. Can we afford to have these players not being regular starters? We already have a 32m striker on the bench, a 16m bum out on loan, a 20m youngster on loan in Turkey and (when Skrtel returns to the starting lineup) a 20m or 17m CB as a sub. So, erm, yeah, seems to me we can stomach that financially, provided we can move these unwanted guys out to balance things up while we shift those incumbent starters onto the bench. Will these guys be happy? That's for Klopp to manage and earn his pay. Injuries and player form will always ensure they get a good share of games anyway. Just ask Lucas.
The replacement cost doesn't necessarily have to be sky high too - the likes of Coutinho, Kante, Mahrez, Payet, Wijnaldum, Alderweireld, etc. illustrate that.
Add pieces to the puzzle, not just changing the pieces and leaving gaps still in it.