As of July 1, Mbappe is officially going to be a Real Madrid player.

I'm very excited about him despite there are still nearly 2 months to go for new season to start.
From now on I really don't know who can stop this team in the La Liga. Normally we would say Barcelona as the biggest candidate. However they lack the strength for doing that. Laporta is also aware of the huge threat now but he can't do anything unless Barcelona finds a lot of money from somewhere. Maybe they can make some money by player sales but I don't know whether they intend to give up on any of their decent players.
Frenkie de Jong has been on the rumours to be sold but it is hard to be sure of it. He is a great player who is quite injury-prone at the same time.

You actually have a point and know that everyone who is in support of mbappe of even Real Madrid will be very excited to see mbappe moving to his next team in order to get prepared for the upcoming season, so to me, I view that Monday as the best Monday for all Real Madrid fans.
Furthermore, I don’t think any team will be able to stop Real Madrid from winning this upcoming La Liga trophy because there is no team that has their strength for now, but we don’t know what might happen before the start of the league, though hope will still be put on Barcelona because we all know that every year they try their possible best to see that they face Real Madrid, and still their president is trying his best to get rid of the financial crisis facing the team, so maybe they will surprise us. We don’t know.
Moreover, they have talented players in their academy, so we should be ready to expect the unexpected from them.