That's why I would go for both. Kimmich now, and Neves in the summer. Phillips will most likely depart this January, and who knows what the future holds for Bernardo. Additionally, Kevin will be 33 at the end of this season. Neves is a young lad and will need time, the same way Kevin will probably start his decline sooner rather than later, because eventually age catches up with everyone. Kimmich could be the immediate answer to our subpar (by our incredibly high standards) form this season.
Apparently, we are not going for Kimmich this month. I hope we can win the title because otherwise, it will definitely be the case of "what if" at the end of the season. I hope we don't regret the decision to go into the 2nd part of the season without a proper Phillips replacement. We are playing with fire here and heavily relying on Rodri's fitness/form this season. Often, it doesn't seem so, but he is just a human and could struggle if we overplay him.
Overall, of course, Kimmich and Neves are not like-for-like replacements, but that's not how we operate. We always evolve and adjust accordingly, but I think the pair of them would be just what the doctor ordered.