The result is that demand for college decreases, therefore the price will decrease through the properties of supply and demand, which leaves an education that returns to being affordable for those who actually care about an education.
You are right that businesses will have to find a new filtering mechanism, but it can be one that doesn't come at the cost of making education unobtainable to those who want an education.
This is a second order effect which I am not so sure which actually happen reality. I posit that it is also likely that people move the requirements to an internal portal, everyone gets wind of such a thing, mainly when HR reps start writing that "breakthrough book" about secrets of getting your first job and everyone still keeps going to college.