Now of course that's not the whole picture, but if push came to shove, the US could achieve energy independence (at least technologically, if not poitically).
The oil can be sold today profitably at today’s market rate.
If there stopped being from the outside competition for the oil, wouldn’t that roughly balance out stopping the supply of oil from the outside?
In the short run, yes. In the long run you’d fuck up the economies of scale and profit incentives.
For these to collapse, I believe we would need the international market for US oil specifically to be substantially larger than the entire domestic market for any oil. Is that true?
You just need U.S. producers to be insulated from international competition.
All solvable, all better than just running out of oil, but I wouldn't call the situation "independence", just "having a better buffer".