I don't want to crap all over your idea here because ambition is good. It's much better to be out there trying to do something different than just expecting a job will be there after college.
But there are a lot of issues with this idea. First off, making money as a freelancer isn't some impossible, Herculean task. Plenty of college kids make money writing, so this idea that it's almost a necessity to write for free is foolish. You'd be better off developing a relationship with your local sports editor than you will writing for this website.
My biggest issue is the fact it'll all be opinion-driven. It might be one of the biggest issues with young journalists today. Everyone wants to fire off a opinion, and worse, thinks they are worthy of weighing in on everything. I'm sorry but more often than not I'm not going to give a **** about what some 20-year old thinks. I don't want to come off as some old-timer here but there used to be value in the columnist because you knew they had experienced some things and it was reflected in their perspective. A 20-year old college junior hasn't experienced enough to be fairly able to weigh in on that many subjects, especially if the website has a national scope.
Personally, I'd be much more inclined to hire a kid who busted his butt stringing HS preps and showing he could actually report than someone who just fired off hot take opinions for this website. Take that for whatever it's worth.
Yup. Show you can break news. That's worth paying for.