Do not hold your breathe. 25% of a gallon of motor oil can be the additive mix and this is not cheaper. A big part of the cost is packaging and transporting it to a store to sell in small retail containers and this is not going to change significantly.
Top quality Valvoline and Pennzoil motor oils are selling for less than $20 a gallon in the lower 48 and that means $20-$25 a vehicle for my two cars and $60 for my truck. Not a big deal and a tiny part of the cost of operating and maintaining these vehicles. The only thing cheaper are the wiper blades.