I think you meant exacerbated - as in global PO was exacerbated (made worse) by wanton US overconsumption.  Of course that has rightly led to the ROW being exasperated (pissed off) with US.

Regarding how poor nations "will" fare - see how they "are" faring - Eritrea, Zimbabwe - already unable to afford oil.  Indonesia - former exporter, now importer, with attendant social/political/economic ills (not that they didn't have ills as an exporter...) I understand South Africa is now having "energy problems".  The UK may be the first "rich" nation to suffer real PO problems.  It's not a "will" problem, it's an "is" problem.  Hitting poor countries first - but we don't care about them, of course.  In the end, the poorest countries will be the best off, because they have come to depend less on petro infusion than we have, and have a better idea and memory of how to get along without it.  

I tend to agree with you, after an initial destruction of agricultural markets, developing countries should do well for exactly the reasons you state also they will no long have to export their food because transportation costs.

just think of all those tea, coffee, chocolate, cocoa plantations..

they could all be growing food for local people, also people will no longer be coated in pesticides which disable 30 million people a year and kill 1 million (see pesticide action network for details).

most of the vegans I have been chatting with are genuinly excited about the "localisation" revolution that is about to take place.

It's not just the destruction of ag markets that will impact "developing countries." This makes it sound so neat and tighty. What will happen will be destruction of lives. Millions, perhaps billions will starve to death, die from disease, or be killed in eruptions of war and civil disorder.

While it is true that, theoretically, there is plenty of ag land to allow a transition back toward self sufficiency, its not like all that land is going to be willingly redistributed back to peasants by caring governments so that they can start farming.