Opinions differ over how to forestall that, or how soon action needs to be taken to forestall it. But not all reform proposals are created equal. To let you test out whether your preferred policies will keep the program solvent for the foreseeable future, the Committee for a Responsible Federal Budget has put together a very fun game (or at least a game I think is very fun) that lets you pick and choose between reforms and see how they affect the program's long-run prospects.
To their credit, CRFB includes not only revenue increases (for example, increasing the cap on the payroll tax or increasing the payroll tax rate) and benefit cuts (like means-testing the program, raising the full or early retirement age, or adopting chained CPI) of the kind that usually get proposed in these discussions, but also ways to increase benefits.
These include creating a minimum benefit for all seniors at 125 percent of the poverty line, indexing benefits to CPI-E (which rises faster than other inflation measures, meaning benefits would rise faster too), and adding a benefit bump for older retirees. You can also just raise benefits by a flat percent, or cut the payroll tax rate by a flat percent. The world's your oyster!