LOL is right. No way! (ETA: I kind of changed my mind on my wording here. Yes, music is probably most important. But I don’t think it’s ok to not to keep grades up.) Admittance is not guaranteed even if you’re a great musician, and at many schools merit scholarships are determined based on grades, in addition to or instead of talent-based scholarships.
Take my advice with a grain of salt, because I’m a newbie to this world and there are many people here who will generously help with expert answers. I can tell you about our experience thus far, because my kid is applying for Jazz Studies/Performance, and he has applied to some of the schools you’ve named. He was admitted to Frost last week, waitlisted at UNT, and is waiting on Berklee.
In addition to doing research about schools, I would talk with your son about his list of qualities he would want in a school. Some are more competitive internally and others are very collaborative. They have many different kinds of campuses and cultures. Some are in music industry cities and others are not. As a jazz musician, he might want to study somewhere like New Orleans or Chicago, or he might want a great program regardless of location. Each has different opportunities for taking classes in other subjects or collaborating with artists in other fields like film. He may not want that. And…you both may or may not know what kind of music program would be best for him to thrive until he gets closer to senior year.
A month or so ago, I wished that we’d cast a wider net, because my son chose to apply to some very selective and expensive schools, but it’s turning out great. He’s thrilled to have gotten past prescreens and gotten so far with some of those schools, and he’s also applied to some that are “more chill” programs, and/or less expensive. He did 13 applications, so he could do all kinds. Some other students do as few as three or four. They know exactly what they want.
If funds are a factor, one thing we have found is that some amazing music programs that are in larger universities can be less expensive. UNT is an example. UNT will give your kid the waiver if grades are solid. If my son gets off the waitlist, it would be a bargain option to consider for a world-class jazz program.