So why would the Saudis let oil slide to below $60 for just a few months? If the plan is too hurt the Russians and Iranians it will be need to be longer than just a few months.
If the plan is to shut down shale oil in the US and a few other places the price will have to stay low for well over 18 months.
Letting prices drop on a short term horizon does nothing but hurt OPEC.