Atm I strongly doubt this tbh.
If the reports about buyout clause and sale percentage are true then money is exactly what he and his father is after imo.
He is an unproven 19 years old so no way we could offer him a lucrative deal. I'd say 100 £k a week max, probably with a backup status contract, not even first team player.
Dortmund on the other hand must view him as a first team player. They'd offer him around 50 £k a week imo.
Which mean over 2-3 years here he would make an additional sum of 5 to 7 £m compared to Dortmund.
I have no idea about how much is his buyout clause and share percentage of the next sale at Dortmund but given that Raiola was involved, the buyout must be not too high to easily move him around but not too low so the shares would be sufficient. And the resale percentage must be pretty high. I'd say 60 £m and 25 % or even more. Which means 15 £m at the least next time he moves to another club. Not counting they'll get another signing on fee, agent fee compared to the move to Utd.
So, it's all about math and money imo. Which should be no surprise considering Raiola was involved.