I really don't think it matters which way this plays out. Think about it - If we are NOT running out of oil, things continue as-is, hopefully with continued improvements for economy and pollution...
If we ARE running out of oil, we will figure a way out of it, I'm confident. The Germans ran low on gasoline near the end of WWII, ground up chunks of pine trees with mechanisms on their trucks, and used the TURPENTINE to run them. Pine trees are definitely renewable.
Fuel from crops (corn/soybeans, etc.) is not a big industry now, but you know how people are - they cram for tests, fail to put stop signs in until someone is killed, don't fill the tank until it's empty, etc. If we are forced to cope - we'll cope.
OBTW - who will "own" the world's best fuel production facilities when we start using CROPS, Hmmmm? It won't be those desert countries, buddy boy. :-)
In the long run, biomass seems like the most promising alternative to oil. But we're a LONG way from producing fuel from biomass that would rival what we're getting from oil today. If we have to go that way, then better figure on riding your bicycle to work. You won't be able to afford the fuel to drive your car.