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.
Indeed. Mbappe is officially a Real Madrid player. Everyone must be curious with Mbappe's career in Real Madrid. Some people think Mbappe won't be successful in Real Madrid because Mbappe is a typical egoistic player. He won't improve Real Madrid performance, he only will ruin the tactics made by Ancelotti. But many people believe that Mbappe will change his mentality in Real Madrid. It is because Real Madrid always know how to build the mentality of the players. Real Madrid also has Ancelotti who knows well to handle the players properly. 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.
Besides Barcelona, Atletico Madrid is the competitor of Real Madrid in every season. Now, we have Girona that can perform well, too. But with the current condition of each team in La Liga, I am also confident that Real Madrid will win the La Liga trophy again in the next season. Real Madrid has improved their squad with Mbappe. Their attacking will be sharper.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. 
There is always rumors about De Jong to be sold. But he still can stay in Barcelona until now. Not sure if De Jong will really move from Barcelona, He looks like to feel comfortable there. In the previous transfer season, he also preferred to choose staying in Barcelona.