The low price of oil is making most oil extraction projects unprofitable to invest in. It the price stays low, it will limit the oil extracted to the fraction which is cheap to extract.

That's good, but the low price also reduces the incentive to invest in renewable energy and increased efficiency. And it tends to encourage investment in burning oil in the future (though that may take years).

Increased tax on oil, or a carbon tax, would give us the best of both worlds: the extraction projects would still be unprofitable, while renewables and efficiency increases would be encouraged.