The laws of supply and demand would indicate that what you propose about collapsing oil prices as being absolutely correct. And I agree with the scenario.
What I do not agree with is that international competition will gain a signficant advantage.
It can be propoerly assumed that Europe and Japan, which constitute the greatest competition would follow the US lead. Actually since these countries already use 25% energy per dollar of GDP, the US would play catch up for a while. In fact, these countries are racing ahead of the US in terms of implementing new technologies because they have far fewer of their own resources. Don't forget a gallon of gas in Britain is $5 and their economy is doing splendidly.
In terms of developing countries - China and India - both also have few fossil fuels other than coal. Indeed, low oil prices would be good for their economies, which in turn would be excellent for the industrialized countries who wish to sell them added value products and services and their rising incomes increases demand.
I firmly beleive that given enough time and support renewables and efficiency improvements will evnetually be competitive with fossil fuels (because like it or not, there is going to be a charge on carbon).
Thus, low oil prices caused by reduced usage in the US, would likely have a minimal if not positive effect for the US economy and evetually lead to more technology exports rather than a comeptitve disadvantage.