Vinicius Jr plays as a winger for Real Madrid, on the contrary, if Mbappe joins Real Madrid, he will play as a finisher. We are only saying this but the club knows very well what will be decided on this matter and we may know the official news at the end of certain period.
Yup, Ancelotti has thought about how he places the position of players. Maybe Ancelotti can put Mbappe as a striker and Vinicius as a winger then push Belingham back. It seems that there are many options that can be made by Ancelotti, in addition to Modric's expiring contract can be filled. There is nothing to lose with the arrival of Mbappe, Madrid will have many player options. That could support Madrid's achievements better.
Believe or not, Carlo Ancelotti is very smart tactician and he cans play well some players not on their real position, Rodrygo had impressive well last several season with Real Madrid and Carlo Ancelotti most of them put him as false nine for central forward although his real position as left or right winger side. I don't think not problem for Carlo Ancelotti if can reach agreement deal with Kylian Mbappe and he will put him as central forward and Vinicius Jr keep at his real position as left winger.
Luka Modric future have been released and Madrid not extend his contract so far, he will be free agent on the next season and his future can't speculated yet because that player not announce yet which one team become his challenge after leaving Real Madrid. Currently, Luka Modric performance not really bad and give him one year contract and he will back up as midfielder position.