It's not an oil slump, it's just reverting to the price that it normally is disregarding short term diplomatic emergencies. You look at the historical price and you will find that it has kept pretty stable with inflation apart from hiccups in the Middle East.
They don't call the shots so much now so it will stay at a consistent and stable price from now on. It will go up to fracking costs or fracking costs will come down to drilling.