Reality check - youth vote was 5% in 2012 Super Tuesday races - certainly to be lower when no black candidate and 2 very old candidates running. Even with recent higher turnout, youth participation is about 18% and lower. Bernie may sew up the millennials (doubtful) but it's halfway insignificant.

Second - states have to pick up half of Sanders' bill - what will they raise taxes on? Will states shift money to college support vs. money for elementary & high school resources?

Third - as Oceankat has noted, most people don't go to college - and if we shift a significant number of youth to college, what happens to jobs that youth normally fill? What happens to those entry wages, and what happens to any that affect competitiveness with overseas companies?

Fourth, if I'm 22, married with a kid working at a factory, or at an Apple Store, and don't have time or inclination to go to college, why should the guy/gal next to me get a huge subsidy for his/her lifestyle choice & basically retire for 4 years?

Fifth, If I want to start my own business instead, will I get matching federal & state funds with no additional requirements too?

Sixth, as someone pointed out, books were the "distance learning" breakthrough of yesteryear. Is a campus-based college the only alternative in 2015, and has anyone consulted a recent study on most effective ways to deliver job retraining and career development? depending on the subject area and type of school, large lecture halls vs. labs vs. small rooms with class discourse vs famous Harvard team case studies vs. stacks of books/papers for the library vs days hacking computers vs. access to specialized campus equipment...  since many people do night classes & eLearning already to get their degrees, what is the right mix to support?

Seventh, with women falling to 25 year low in job participation but pushing 60% of college degrees, is this subsidy expected to provide economic benefits or support essentially educational entertainment? (if the latter, what other lifestyle options should be subsidized, such as yoga & fitness clubs, volunteer/charity work, shopwork, unpaid internships, etc.?)

Eight, what bloodsuckers will appear to exploit this subsidy to provide rather meaningless "college" that takes a good chunk of taxpayer money? How does it affect the balance between full 4-year schools & junior colleges, and the balance between top-rate schools and more local community college.

Ninth, while seemingly a small percentage, what effect will this money have on stock exchange value, trading patterns, competitiveness with other exchanges, and particular types of instruments (e.g. fast trading will now contain more overhead than buy-and-hold-em investments, and strategies like stock options portfolios might lose some of their appeal). What will Wall Street do to get around this, killing off revenue?

Tenth, why just pick on Wall Street?  How about a 0.5% tax on every military transaction? Much bigger money, and typically much less beneficial to the economy or the planet's well-being.

From my end it will be a bit galling, as I got almost no support for my degrees, but my father got GI BIll and my kids will get college support.

Anyway, a few questions to mull over, including is making college free the right goal, or simply returning it to affordable and using similar tax-the-rich approaches for equally deserving priorities?