Is it a must to speak a foreign language in order to be a sport analyst and be in the broadcasting industry?
It isn't a must, but it would certainly help set you apart from other applicants. Additionally, consider today's athletes and how diverse their backgrounds might be. While you may not be fluent in a second language, could you pronounce names in an authentic manner? It matters to the viewer and certainly your eventual employer.
Going off of what Roman said, it's not a must but it's a very valuable skill to have. For example, if you can speak more than one language, you're not limited to just production and opportunities are open to you in bilingual production (Spanish speaking networks, etc.) My one regret in college is not pursuing a minor in Spanish after already having 10 hours of college credit from passing the CLEP exam.
It's not a must but like everyone has said it's a great skill to have and it allows you to future proof your job security a little more. Learning a second language, particularly Spanish if you're referring to U.S. broadcasting, is something you will always use throughout your entire life both in and out of the workplace.