I would have to disagree that a third of the farmers would go away.  The larger operators would possibly give up some or all of their rented land since they could no longer milk the system.  Without subsidies, land price and rental would tend to settle back to a level that is affordable for most and profitable for all.

Farm programs right now send lots of dollars into farm operations that are so large that weather like this spring keeps many from getting all their planned planting done.  Break those operations down to more farmers, acreage gets planted and young farmers (below 35) get a chance.  I am by no means large, and if you take away my subsidies, I wouldn't even notice.  Have never used government dollars to justify purchases, land or otherwise.

There are too many fine young men and women not able to farm even part time due to farm programs making the large farms larger and driving the small farms out of business.  I know that experience all too well from my first years out of college.