I am not saying it will be easy, but the odds are pretty much on their side, considering how strong they are, and the mentality that they have created for themselves. The loss of Nacho and Kroos won’t really affect them much because of how their squad looks now.
I don't doubt the mentality of champions like Madrid in the hunt for the UCL next season, what you said is also true, the loss of several players and the arrival of new players seems quite balanced, in fact this team is actually much stronger and better for the new season, the arrival of Mbappe also has an impact also for their front line, Ancelotti may have experience in how to arrange star players in the first team and follow the strategy he wants, even though many people say he is poor in tactics but it seems he has a lot of experience and knows how to rotate his players correctly.
Madrid will still compete with Manchester City because for me Manchester City is a team that also has the opportunity to win the UCL trophy in the new season, because their failure last season when Madrid beat them in the UCL quarter-finals meant they had to go home first, even though I hoped Madrid would meet Manchester City in the final but unfortunately that didn't happen and they met in the quarter-finals, we may not be able to predict Madrid's strength at the start of the season, not all players can quickly adapt to the new players on the field.
It cannot be denied that Real Madrid does have a winning mentality. With several La Liga and Champions League trophies in the last few seasons, that has proven it all. With Mbappe joining them, it will further strengthen their front line but I think it will not be easy for Real Madrid to find a replacement for Toni Kroos, and I think something will change with their game next season. They still have Luka Modric, but he is not in his prime anymore.
What is quite interesting to see is whether Carlo Ancelotti will try to find a replacement for Kross because the transfer window will still be around for quite a long time or he would prefer to provide a new formula with all the resources he currently has.