If your employer is a company that's still in business when you retire, it will make the payouts. There's a federal law called the Employee Retirement Income Security Act, or ERISA, that makes sure of that. Still, it's possible that your company might run into a financial mess that puts your defined benefit payout in jeopardy.
That's why most pensions offered by companies are part of the federal Pension Benefit Guarantee Corp. Much like the FDIC insures bank deposits if a bank fails, the PBGC will step up to the plate if a company goes out of business or declares bankruptcy, and says it doesn't have the money set aside to pay all the future benefits you expected to get when you retired. The PBGC insures the pensions of more than 44 million workers in more than 29,000 private defined benefit plans.