I'm still not convinced.
Let's look at an optimistic take:
Boban got fired for saying Rangnick was signed. Could have meant a pre-contract agreement, but his wording was very specific about him being the next coach and director.
The statement from Rangnick's representative was very weirdly worded:
"AC Milan and Ralf Rangnick have agreed that it is not the right time at the moment and that there is no momentum for working together. Because of this and taking into account the good development and the results under coach Pioli, it was jointly decided that Ralf will not take on any role at AC Milan"
It implies that the only thing that's blocking the move is that it's not the right time because of how well the team is doing. Let's think about why this is.
Pioli is at his absolute peak in terms of reputation and sporting success with Milan. He's doing incredibly well right now and rightly deserves to be the manager for next season. Ralf taking over in August at the end of the season would be both very unfair to Pioli and also to Ralf. He would be basically handed a poisoned chalice. If he wins and continues the success of Pioli, then people will say it's Pioli's team. If he fails then people will say it was a mistake to drop Pioli. It's just a shitty situation. Nobody predicted how well we'd be doing after the lockdown.
Now lets look at the money. Pioli has a contract until summer 2021. There's talk now that it will be extended, and if it is extended then everything i'm saying here will be wrong. If Pioli is fired in August then Milan will still have to pay his salary for the year or negotiate a termination. So they're paying him no matter what. Rangnick has a contract with RB until summer 2021 also, and he needs to buy himself out of it to get out early.
The success of the team right now makes it less urgent for Ralf to take over. Keep Pioli in charge for next year. If he keeps winning, great. If not, then Ralf takes over and it would be a much better time to do that. Same for Maldini also, they would have paid his salary anyway, so why not just let him continue his work since he's doing great anyway.
This could just be wishful thinking of someone still in denial, but it seems reasonable to me. We're not in a hurry to make this transition and doing it in August with Pioli doing so incredibly well right now would be a disaster.
Edit: Lol just as I wrote that they signed Pioli to 2022....