I mean....it might happen? But there, once again, really doesn’t seem to be any evidence that the aim is to eventually drop Henderson and Gini (who I assume you’re referring to as two of the three ‘sixes’?) from the first choice midfield.
Hard to predict what happens if both Keita and Ox are able to perform to the level expected on a consistent basis. Do we just rotate the midfield? Or does someone give way? All of our options in midfield bring a slightly different set of skills to the table. Overall, Klopp seems to prefer the balance of responsibilities over playing any given individual. So if you put in Oxlade Chamberlain, you gain in attack, but lost a little defensively. That's fine if the other two in the midfield are able to compensate.
I think there are still people who expect Keita to be an all-out attacking midfielder, but that was never likely in this side. Of the other players in our midfield, I think he's closest to Wijnaldum, a player with the ability to cover defensive and attacking aspects of the game.
I rate Henderson, but there are things he does not do particularly well in this team. It's less of an issue when Fabinho is in behind, but ultimately, I could see Fab, Nab and Gini as the most Klopp-inspired midfield combination.
Then we just need to see if we can fit Grujic in as well...