Well, Mike was an expert in bending people to his will, so he could have tried to interfere with Anthony.

But his arguments were deeply weird for a super-rich bloke. Law degree is an insurance for people who have to work for the living and scramble to pay for it. Ditto the risk of failure in a musical career.

I mean, if Anthony failed he could have gone back to law school or business school or go into business/politics or whatever, really. I am sure that Michael set him up with a nice trust fund and stock in the family corporation.

I don't see why it was even worth an argument on Mike's part, except that Coppola wanted to set up a confrontation with Kay. But he really should have come up with something more sensible.

Ironically, in the book Michael thought that he'd be glad if the next generation of Corleones became college professors or musicians, not just lawyers and politicians... And he never wanted his sons to inherit his criminal empire as he seemingly did in GF II, quite the opposite, he intended to take steps to ensure that they'd never be tempted.

Oh, and Luciano Pavarotti debuted at 26 after 6 years of singing training, so debut at 27 isn't completely out there for a tenor.