For the midfield, it actually won't be too much of a problem for Madrid because even if the worst possibility of Modric and Kroos leaving next season but Ancelotti has minimized it from the start by doing some rotation and habituation to his players when there is no Modric and Kroos from the last 2 seasons and their young players also in midfield are still very good now where there is Tchouameni, Camavinga and Valverde who can be maximized so even if they do not add a midfielder it is still not a big problem even though ideally there are several players who are brought later but indeed for now Madrid's focus is likely to still be on the attack and defense.
You're right. It won't be a problem although Kross and Modric decide to leave Real Madrid at the end of this season. Real Madrid has enough midfielders, there are 4 midfielders who can replace the position of Kross and Modric. Ancelotti already prepared a long time for the possibility of Kross and Modric will leave Real Madrid. Tchouameni, Camavinga, Ceballos, and Valverde are enough to be the successor of Kross and Modric.
At the moment when talking about Mbappe it is still hanging because with what is happening now Mbappe in Madrid is also still uncertain even though there is a very big chance to join Madrid for Mbappe but we know that Mbappe and PSG always do drama every season especially when the transfer season takes place.
I think it is clear that Mbappe will join Real Madrid. The latest news I heard, Mbappe already got a personal agreement with Real Madrid. It means Mbappe agrees to join Real Madrid for the next season. Now, PSG can't make any drama because Mbappe's contract expires. Mabppe will leave PSG with a free agent status.