Yep, it's true: We may be light on Fighters. The United States Air Force, like the Navy and Marine Corps, is keen on landing the newest models. Over the next 25 years, that is. Meanwhile, the current fighter aircraft are thinking about their golden years of blissful retirement.
The Congressional Budget Office (CBO) has published a study that addresses the DoD plans, as well as budgetary, as well as tactical, concerns. You can see the report, Alternatives for Modernizing U.S. Fighter Forces here.