A heck of a good run! Glad he is going to be able to enjoy his retirement and still be an ambassador for Mario. :)
Since the voices in Mario Wonder are apparently the new team, I'd say they picked some good replacements. I didn't even realize it wasn't Charles in the Wonder trailer!
Overall I'm not saddened by this because he had an amazing career as Mario (and still perhaps as the many other characters he's done). There was always going to be this day and I am glad they're not trying to AI him into forever.
I just hope, like you, that this went down in a very good manner. I want him to be happy with the forward changes and I want Nintendo to be fully respecting him on every level, salary or otherwise.
I'm excited to see what the world holds for future voice artists. Maybe we'll get to know the new person/team soon enough. I hope they have a great personality like Charles does.