I think the other consideration from Madrid's side is that Florentino won't stand still and if Vini signs a new deal it will make it awkward to add a huge attacker like Olise next summer. Its already very hard to find the right balance with three attacking superstars in the same team, four is just impossible video game stuff. Given that Florentino seems totally committed to both Mbappe and Jude, its a question of who complements them the most and the answer is really clear once you think about it.
Mbappe, Jude, and Olise has a great balance of scoring and creating and is also balanced in terms of players preferring different sides of the pitch. There are also a lot of different ways you could set up. You could play Mbappe LW and have a facilitating focal point CF, play Mbappe LW and Jude as a false 9, or play Mbappe CF and have another LW player (Diomande?) supporting the stars. This is the closest Madrid can get to approximating the balance of the BBC trio.
Mbappe, Jude, and Vini is much less balanced in terms of scoring versus creating and, especially, in terms of locations on the pitch, as all three players shade to the left. There's also not many different ways you can put them all into the same team unless you want to start pushing Vini to the RW or something. It almost has to be Vini LW, Mbappe CF, Jude in advanced midfield with all of them drifting into the same left channel and left half space areas.
Obviously this is also what I WANT to believe as an Arsenal fan. But I think there's some merit to it, especially if Florentino has a strong belief that obtaining Olise will be possible next summer.