Maybe, and we're about to find out pretty soon. But I that type of upgrade will happen this summer. I'd be surprised if it didn't.I don’t expect both Keita and Ox to be fit all of next season, but I do expect much more from them than we got this past season. Ox was out the whole time, and Keita only saw limited action as he took a long time to get up to speed. He was starting to look good before Rakitic scissor tackled him out of the CL semi and ended his season.
Once Fabinho found his way into the side the midfield blend started to look better. Add Keita and Ox to that and we are in business. But since there are question marks over their fitness, Henderson and Wijnaldum (who had a good season) ahead of Fabinho isn’t terrible, and we will see a fair amount of that, or one of them and one of Keita/Ox, depending on fitness and form.
All that is to say I don’t expect a big change to the main midfield personnel for next season, but I do expect us to get more out of the group that we already have here. By summer 2020 we will know a lot more, and perhaps at that point we will go big on someone like Havertz, or Aouar, or whoever, as Milner waves goodbye.
I see the merit in what you are saying, but I don’t think we will tackle it this summer, due to the various permutations in play I’ve tried to lay out.
Another forward, probably of the fast, goalscoring, versatile winger variety, will probably be the main signing, plus other back up roles where we don’t have the depth we need.
But the way you worded that bit "isn't terrible" is my point exactly. No, it's far from terrible. But I think that conveys that we can definitely upgrade it. It really does hang on the conversation Klopp and his whole team, not least his medical staff, will be having about keita and Ox