I think the possibility of Tuchel leaving is higher than Kimmich leaving. Kimmich is one of the players who most strongly oppose Tuchel.
Tuchel leaving Bayern Munich is no longer a probability, is it? I think it's certain that he's leaving. It has already been announced by Bayern that Tuchel would be leaving at the end of the season and Tuchel himself has confirmed this.
I believe Kimmich too might leave but there's still a chance of him remaining at Bayern. If a manager who has a good relationship with him is appointed, he would most likely stay, but the chances of him staying are not very great.
Another player that has a slim chance of staying is Davis. I know Davis already has his eyes on Real Madrid at the moment.
What I know is that Bayern won't let more than 2 important players leave their club this summer. These kinds of players are difficult to replace so they'll do all they can to convince them to stay.