I agree with what you said, they certainly can do that and you could argue the last crude crash was motivated by the US boom. The other argument is that Saudi Arabia's main objective is capturing as much profit as possible on all of their reserves before demand falls off a cliff vs strong-arming competition. They don't want to be stuck with huge deposits nobody wants in 30 years. It's their only export and they will stimulate demand as needed to sell every last drop. In this case, undercutting others would be a side benefit.
Well that's the trillion dollar question. Renewable energy adoption and carbon regulation are accelerating. I'm struggling to see a scenario where we run out of reserves in this century. I wouldn't put it past a country almost completely dependent on oil to keep stimulating demand.
