If Viktor Bout’s empire were put out of business, the flow of weapons to the world’s trouble spots would not grind to a halt. But it is unlikely that a similar network—a large, vertically structured organization capable of door-to-door delivery of advanced weapons and hardware—would emerge in its place.

Instead, the world of arms trafficking would return to the way it was during the Cold War. No single weapons broker could offer the full range of services that Bout does. There are several reasons why. For starters, the world is more aware of transnational threats today, and a new Bout would likely be spotted and stopped earlier in his career. Although Russia is still awash in weapons and aircraft, it is no longer the Wild West it was when Bout staked his claim in the early 1990s. Many areas of Africa are now so saturated with weapons (many of which were provided by Bout) that their value has dropped markedly. For example, the price of an AK-47 in the Niger Delta region has dropped from $250 to $75 in the past 18 months.

Future operators will likely have to create business models with more middlemen and fewer profits. The more steps there are between acquiring weapons and transporting them, the more opportunities there are for law enforcement or intelligence agencies to break up international weapons cartels. If the profitability of the weapons trade diminishes—in part because of the success of traffickers such as Bout in meeting the market demand—transporting weapons will be just one of several portfolios for illicit air merchants.

Like Bout, future gunrunners will probably have to rely on both legal and illegal cargoes. There is a severe airlift capacity deficit across the world, making ownership of aircraft as valuable as the weapons they carry. That means legitimate business...