From giant companies like Exxon Mobil Corp. to OPEC members such as Saudi Arabia, oil producers say their industry will enjoy decades of growth as they feed the energy needs of the world’s expanding middle classes. But what if they’re wrong? There’s a host of reasons to think they might be. Here’s what happens when you test their central assumptions. The International Energy Agency sees oil demand rising more than 10 percent, to 103.5 million barrels a day by 2040, while companies predict even faster growth. But forecasters don’t always anticipate seismic shifts in technology and policy that could slow demand growth, or even eliminate it altogether in some parts of the economy. Even small changes could add up. Advances in vehicle efficiency, a rise in electric cars, tighter emissions standards and shifts to other fuel sources would result in oil demand much lower than the industry is banking […]