I am not an economist (which will be made abundantly clear).
It seems on the surface that the recession started with high fuel prices. Prior to the collapse of the housing market, gas prices reached more than $4/gallon and it was hurting a lot of people. Now, the bursting of the housing bubble could have been foreseen. When I bought my house in 2003 I opted for a 30-year fixed-rate mortgage, because I had no idea what interest rates would be like down the road – except that rates were so attractive then that I thought they could only go up. But the housing market didn’t fall down until half a year after gas prices peaked.
So: Would the housing market have crashed when it did, or would it have been as severe, had fuel prices remained low(-ish)?