Answer: racial upheaval and violence.
The phrase "pay the bill" refers to paying for one's own expenses. However, in this case, the phrase refers to making up for a mistake, or facing the consequences of one's actions. By saying that someone would have to "pay the bills," the character implies that there has been some bad action and that someone will pay for it. This most likely refers to some act between blacks and whites, and the payment will most likely come in the way of violence.
