If the barrel price stays low for about 5 days then pump prices will indeed go down too.  It just takes a bit to move through existing inventory.    No idea if it will be "the lowest in decades"  but it will get low.   I recall toward the end of Obama's presidency that price/barrel dropped to about $30 and pump prices dropped to about $1.85 per gallon here in NC...  In SC, who has no gas tax, got down to like $1.40. You can go here and look back at historical trends and clearly see that the pump prices respond to barrel prices pretty quickly.