I think that first, it's important to divorce the idea of the Wandering Minstrel from Yoshi. The Wandering Minstrel is an avatar for Yoshi P, but more than anything else he is a role played by Yoshi to give thanks to the players. The Minstrel himself has no power that we have seen in the past, though he does take inspiration from the Warriors of Light. Suddenly turning him into a superpowered boss and having him fight the Warriors of Light would be jarring and out of place.

I do think it could be reasonable to fight Yoshida in a special event of sorts though, separate from the plot and with a grain of satire. Having Naoki Yoshida fight the Warriors of Light on his own terms would be very interesting. He plays a Black Mage, so it would be an interesting idea to go up against a super-powered caster able to cast Meteor at will. It would be fun to brainstorm ideas of how to introduce the ideas of a God in the game by introducing existing strategies in new and exciting ways while referencing older battles. The fight against the SE President in FFXV is an interesting addition as well.

It may be no more than a pipe dream, but it's a cute dream to think about.