Kroos was and remains a unique player, by the way he does not forget to mention this when he gives interviews and says that Real still has not found a proper replacement for him. But on the other hand maybe there is no need to look for someone exactly like that, maybe Alonso will bring something new to the team and there will be no big need for it. And Kroos continues to work at Real just like he said he would, he is involved in developing young players. I think for Real's youth academy it is a huge advantage that a player of this level keeps working with the team even after ending his playing career.
Xabi Alonso may not be looking for someone who is truly like him. But Xabi and Real Madrid really need a replacement for his position, because of the importance of a playmaker in a club, the better the playmaker, the better his playing pattern will be, and also the more effective his attack and ball possession will be. And this player is what is being sought and expected to be at Real Madrid for the future. Xabi also revealed this, that's why he wants Vitinha who can fill his position more appropriately, but once again, PSG will definitely not let him go.
Source: Xabi Alonso - Tony kroos