There's a lot of good points in this thread, and I largely agree it's time to move away from the old guard of Henderson and Milner. Both have a role to play, but we should not be dependent on them, especially the later. I'll always stand by the Thiago signing - he's been excellent when here and we're a different side with him in the team. His record with Fabinho in terms of wins is proof enough.
The issue then is that of the supporting cast, in particular Chamberlain and Keita, and the clubs inaction over the pair of them. These are the players we spent big money to take over the reigns of the likes of Henderson and Milner and yet they cannot. This has been obvious for 2/3 years now, but Klopp and the club have stood by them, stubbornly refusing to cut their losses, and then compounding the issue by letting Gini leave. The drop off of Henderson and Milner was inevitable. The inability of Keita and Chamberlain to step up was largely predictable. The club did nothing. Our club get a lot of praise for our squad planning and buying policy, but there's been some huge flaws in our approach to midfield. In short, Henderson may well be the issue now, but the problem was set a number of years ago.
Too often Klopp and backroom team are overly optimistic than injury prone players can be counted upon.