Mbappe can play in Vini's position, but he can also play as a central striker. He can play in some positions, which makes him very dynamic depending on what strategy the team implements. For example, when Enrique ordered him to play as a central striker, Mbappe was doing it.
The same thing can also happen in real madrid when the club doesn't have someone who can play as a number nine. mbappe can fulfill this position that is currently filling by joselu. There is no problem when Mbappe is placed as a central striker under Ancellotti caused by Mbappe is very capable of doing it.
Mbappe is very flexible, which makes him different from the other players. He can play in various positions, which is really helpful when the club needs an urgent striker to play at the bottom.
Regarding Vinicius Junior still in Carlo Ancelotti scheme for the next season I think Mbappe will put as central forward, but its not problem because Mbappe can play well what ever position as left winger or central forward. Latest announcement from Fabrizio Romano, all expectation running well and right now Madrid have discussing well reach agreement deal for signing Kylian Mbappe. Just waiting release and official announcement from Real Madrid and Kylian Mbappe have reached agreement deal and detail how many years contract.
Its most amazing if Mbappe will join Madrid next season and there are have three attacking line from Vinicius Jr, Mbappe and Rodrygo will make most danger attacking players having by Madrid, we will see the best trio because Madrid had the best trio before with BBC, Benzema, Bale and Cristiano Ronaldo.
It's very long time we are waiting for this decision and official statement from the Real Madrid with now in last few weeks we are having another rumour as Vini is also not happy, and he is looking for the new club which mean things are starting on wrong side for the Real Madrid with the arrival of the Kylian Mbappé because their star player is feeling not good and want to have his place better at any new club and two English clubs are named for his next destination which is interesting even until we will not have anything official we can't give any response, but surely this move is going to create something behind the scene for the Real Madrid as well.
No doubt this could be historic deal and Real Madrid which will be also good beneficiary of this with they are going to have Mbappé as free agent and PSG is also now looking for the new star Real Madrid is always having top quality players which make their mark in the game and give them best ever results as well.