Put it this way, many diffs ago, on a lucky day in mining, you could earn 10 bitcoin in one day or 1 bitcoin on a bad day with 60GH.  In today's diffs, even if they fluctuate a little instead of just going up, there is no way in an eternity you could ever make up those 9 bitcoin with 60GH unless you used your avalon as a weapon to hit someone over the head and steal their money.

The next block halving will probably be the only time we'll ever see a significant drop again (unless BTC value crashes). What effect that will have on a tight margin network (unlike the GPU days) is unpredictable.