This report http://theconversation.edu.au/oil-oil-everywhere-but-still-no-such-thing-as-us-energy-independence-10731 provides some good arguments why the US won't "become a net oil exporter by 2030"
- the International Energy Agency (IEA) and Institute for Energy Research (IER) have been wrong in their US energy self-sufficiency predictions before. Instead according to "...the Energy Information Administration of the United States Department of Energy, the US will remain dependent on imports for about 43% of its oil consumption even through 2035."
- an excessive amount of unconventional US oil and gas on the world market would tend to lower international (including US) oil and gas prices. The US government and industry might instead decide to limit the amounts released on the market to keep prices high and thus earn higher revenue.
- lower than predicted oil prices would make prospecting and extraction of unconventional oil and gas in the US uneconomic.
- domestic political opposition on environmental grounds to such processes as fracking.
- cheap, plentiful US energy exports might cause much higher US consumer use thus increasing greenhouse gas levels that world cause negative reactions to US production from foreign governments.