You've figured it all out, it seems
We'll never get Donnarumma for that amount with Mino around, and with a major rebuild coming fast around the corner for Real, I refuse to believe that they'll sell either of Isco/Asensio. They are ascending for superstardom
I haven't figured anything out but I did made an educated guess. So lets tackle your enquiry first. Real doesn't seem too bothered losing up homegrown top talent. Else how could you explain them letting Morata (13 goals in 32 matches this season) go? Now according to whoscored Asensio had played just 9 games in La Liga this season 7 of whom coming out as a sub. Do you think the boy will be happy rotting on Real's bench especially since
a- many clubs would love his signature include us
b- they seem to be quite busy courting the likes of Neymar, Hazard and god knows who flashy player is in fashion at the moment.
I doubt it.
So here's what I think.
A- Donnarumma wants out. Raiola had taken things too far with Milan and he knows it. Thanks to him all Italian clubs had turned against the boy so unless Mino figures a way to get him out of this mess then he risks losing the player for good. Now Donnarumma has two clauses. One is 100m euros but that applies only if AC Milan makes it to the CL (AC Milan are currently 7th, 10 points away from 4th place Inter). The other, more realistic minimum clause is that of 50m which will activate once the obvious occur.
B- I was expecting Mino to go ballistic regarding Mkhitaryan. I mean he went ballistic about Donnarumma despite Milan showered the boy in gold coins, gave a job to his incompetent brother (ok we did the same with Phil but that was under the illusion he was good enough for us. AC Milan know that Antonio Donnarumma is shite) and accepted every single clause he wanted. How could this guy stay calm and relax as his 'beloved boy' moved to Arsenal like cattle? You have to admit that is at least suspicious.
C- Real had the unique opportunity to sign two promising keepers but they barely made any moves whatsoever. Kepa who was on a measly 20m minimum clause had just signed a contract. Things seemed so close for the boy but he rejected them. Donnarumma was available last summer and Mino paraded the boy for them. However Real ignored him. Its evident that they want a ready made solution which comes with no surprise considering we're talking about Real here.
D- I cant see DDG signing another contract with us and United can't allow him to leave on free/cheap so this will be his last year. United won't sell cheap though and as many said Real Madrid will be too busy spending the dosh upfront to afford 100m. Considering that they don't even bother playing Asensio and are still courting top players despite having him around then it doesn't seem that they rate him too much don't they?
The only thing that I feel could change everything is courtois. He's the closest available thing to DDG. There again if you had to choose between the two whom would you sign?