This time Real Madrid failed in La Liga and they got bad results, especially during recent games we saw from this team because even lost their place in the second position of the table in the other hand there is no hope for them to win the La Liga title, however, they won the Copa del Rey but being in their place of the tale is not good for a team like Real Madrid, I think there is a high chance for Ancelotti to leave Real Madrid if they don't win the champions league because of the bad performance they had so far.
Real Madrid this season has experienced ups and downs so that it can be left far behind by Barcelona in the competition for the La Liga title. Even though later Madrid have to finish in 3rd place, I think everyone in the Real Madrid environment has accepted it. In such conditions, no one needs to be blamed, including Ancelotti, because he has done a good job so far. This season El Real's management also did nothing in the transfer market, so being able to win the Copa del Rey was also very good for Madrid.
Apart from that, if they also fail in the Champions League then Florentino Perez should retain Ancelotti. I see that currently it is quite difficult to find a classy coach on the market, if indeed Perez also has to kick Ancelotti then that is a very big gamble.