How likely is it to be a sports commentator?

I don't know the answer to this but if I were you, I would make a list of Sports Commentators you respect and reach out to them on Twitter to ask questions. Also, find a few locally you like and ask if you can shadow them for their next game to learn more and take notes. Identify yourself as a student for a better chance of response.

Ask your school counselors and Athletic Director if they can arrange some opportunities for you to shadow some sports commentators. Start with the commentators who call the games for all different sports at your own school.

The answer is highly unlikely unless you pursue this career. Getting what you really want takes hard work and time. Becoming a sports commentator may take many years. Start in high school or college. Some high schools have radio stations. If not, then go to a university with a communications program and become involved in the radio station. Even if you have to volunteer, find opportunities to become involved in the field. This can take time, but if that is what you truly want, then make this your goal and keep working.

....very likely... start a broadcast; make yourself stand out; make yourself different from the other sports broadcaster. Remain focus on your dreams and it will come to fruition. Best of luck!