skvidal: The saving grace is that (1) you don't need oil to fix nitrogen, you only need electricity; (2) You can fix nitrogen anywhere you can get electricity, even out in the desert or on the deep ocean. Fixed nitrogen can be transported as cheaply from those places as from wherever it's being made today. Wind, solar, ocean-thermal, and geothermal power are at their most practical far from populated places, and nitrogen fixing need proceed only when there's power available, e.g. when the sun's up. Fertilizer supplies won't crash, but will get more expensive.

I expect wind power to get much cheaper soon, via e.g. Makani kites. Solar thermal is already practical and cost-effective.