The Ninja Turtles attempt to thwart the schemes of the Foot Clan. They are (due to the inverse ninja hypothesis) almost impossible to defeat. In order to override, the Foot thereby has to put a tremendous amount of time, money, and energy into the purchase of more ninjas.
It is unlikely that the Foot can independently produce all of these ninjas, and so they turn to outside contracts. These outside contracts exist, not for the purpose of enacting the wishes of the foot, but to generate a profit. Luckily for them, ninja production is an ancient and secret art, so there is not much in the way of competitive bidding. And so you have a handful of ninja-production entities that provide Foot Soldiers, trained in the ways of the ninja.
However, this is where that profit motive comes in. The mass production of ninjas require a standardization of ninja standards. Because not every ninja can be cool but rude, or a radical rat, the standards for ninjas must be the lowest common denominator. This is precisely was the ninja-industrial complex sets itself up to produce: a ninja that can barely pass minimum ninja standards with the minimum of training, thereby allowing themselves to reap the maximum profit.
This produces a self-perpetuating cycle. The disposability of the foot ninja means that a huge number of them are required for the simplest task. This generates a huge demand, which keeps the overall cost of a ninja unusually high. In order to pay for these high ninja costs, the Foot Clan leadership (generally Shredder) is required to engage in larger and more dangerous operations, in the hopes that they will be more profitable. These are precisely the sort of operations that allow the Ninja Turtles to brutally devalue a large number of foot soldiers, requiring the purchase of even more foot soldiers. This, in turn, requires Shredder to purchase more trained foot soldiers, which he then has to pay for by having them take powerful or expensive things, which allows the turtles to devalue them, etc.
Perhaps the Shredder will not, himself, even use the power of all those artifacts he's after. He just needs to sell them to pay off the interest on his deficit.
In this system, the worst thing that could happen to the system would be the elimination of the Ninja Turtles. Without them, the expected life span of a foot soldier increases exponentially, and demand drops. In top of that, the Foot Clan may suddenly find that it can accomplish it's goals with a small handful of in-house trained ninjas of a higher quality. Ninja demand diminishes by an enormous amount.
The ninja-industrial complex, however, continues to be set up to mass produce ninjas at minimum cost to itself. In order for them to stay solvent, they would need new buyers, and would have to be willing to accept lower profits, as their low quality goods are suddenly exposed to the cruel laws of supply and demand.
The result would be a market flood of inexpensive ninjas. As a ninja is not, strictly speaking, a single use good, all manner of uses could be found for them. Ninjas could find themselves employed working club security, or being members of pop-star entourages, or helping your grandma go grocery shopping. The extremely low price of the ninja would make it a dream that all Americans could share: a chicken in every pot and a ninja in every garage. A ninja would be your first choice for any mindless task that required a warm body, but not quality. This would include working for low-rent overlords, standing in the woods holding directional flags for some really lame contest. Clearly, Gymkata is a post-Ninja Turtle world already.
Note that "Ninja Turtle" could probably be replaced with "Steven Seagal" with no particular issue.
