I heard a commodities broker say that oil can't go above $75/barrel, because at that point it becomes economically feasible to turn coal into oil. If he's right, oil could spike to $100, but it couldn't be sustained at that level.
While those means could be built, not many are going to rush out and invest in a processing plant that is guaranteed to lose 1/4 of its projected revenue, just by virtue of going into production and causing the price to drop, and may well cause speculators to bail out and leave the plant incapable of recovering its construction costs.
In a way the quandry is similar when drilling oil wells, but the investment to drill a well and bring it on line is so much less than that for a synfuels plant, there is usually time to recover the venture capital before the well (or a large number of them) impact commodity prices.
If oil prices crash, the derricks are laid over and the drilling rigs mothballed until prices come back up and operators want to drill wells again. You can't do that with a synfuels plant if it has not reached payout unless you have verrrry deep pockets.
Would the plant pay for itself at $75 per barrel? $65? and what rate of return would that bring on the initial investment? Given a choice, I'd build an oil refinery.