Once a walkon earns a scholarship is that scholarship not guaranteed for the remainder of their eligibility? Has Nebraska ever gave a walkon a scholarship and then the next year said you have to pay for school now?
it really depends. Sometimes it's just because they have an extra one and someone deserves to have it for a while to make it a bit easier for them for a semester at a time. These usually are just temporary.
Other times it's a guy who maybe was considered a preferred walk on who was to be given a spot if they hit the 2 deep. Those guys tend to stay on scholarship (think Scott Shanle or Spencer Long type players)
Another thing that happens a lot is that they will roll some guys onto scholarships that are available in the spring due to graduations, etc.