As others have said Ferrari used Agip for a LONG time. 60 years of Shell, sorry untrue.
As for oil companies bailing out, sorry will not happen. The car is a billboard with space to be bought. And they can still legitimatly promote their lubricants. Most people know that petrol is petrol, often far from what is should be too. Made in a refinery in a cheap labor area and trucked in to outlets by generic tankers.
Nascar fuel is far from pump petrol. V8 Supercar fuel is an ethanol fuel. Works ok but they stop every 45 min for a refuel. And again is far from road fuel. I believe the average family hack will run on either but probably not very well. The E85 probably the best.
Personally I feel a spec supplier of 'normal' 98 octane premium road car fuel would not hurt. Slow them down some. Either that or generic 100 octane Avgas as was once the standard anyway. jungle fuels are hardly applicable to the real world.