The [main] reason tuition is high is because of supply and demand. The reason we have graduates in thousands of dollars of debt who can't find a job according to their degree is also because of supply and demand. Free tuition would not create an equilibrium to solve this problem, amirite?
On another note, it could possibly help employers. The market could become saturated with potential candidates who otherwise would not have had a college degree. This would give employers a more broad selection. This would however hurt the individual who will find it challenging to stick out among a higher population of people with degrees.