That something is not likely to be a major free agent signing or trade. I see fans warming up to the idea of acquiring Darrelle Revis again, or signing a short-term option like Antoine Winfield. While there's nothing inherently wrong with either of these scenarios, they would cost the Falcons either draft picks and other assets or cap space. Both of those are problematic.
The first scenario would require the Falcons to give up multiple picks. Forget about packaging a player, because if the Falcons swapped someone of value to the Jets, they'd be down another piece they'd have to take care of, but with less draft picks. It would also require the Falcons to pony up for $10 million or more a season on a long-term contract. Even if Matt Ryan gets his extension this off-season, it's not going to cover that much scratch, regardless of how creatively Thomas Dimitroff works it. I'd consider this extremely unlikely.
The cap space rears its ugly head again in the case of a player like Antoine Winfield, a fine cornerback and an intriguing short-term fix for the Falcons. Even if he comes cheap—and he will—the Falcons can only fit so many more contracts without cutting into space for their rookies. Winfield is also only a short-term solution, and he may sign somewhere else by the time the Falcons free up room with a new Ryan deal, anyways.
All of this makes it exceedingly likely that the Falcons will choose to try to spackle their current hole with a young, dynamic cornerback from this year's draft. The draft is chock full of options, including promising first-and-second rounders like David Amerson and Desmond Trufant and guys further down, like some dude named after an animal that everyone tells me should be drafted.
I fully expect the Falcons to spend one of their first three picks on a cornerback, and it will likely depend on what kind of asset they view Robert McClain as going forward. What do you expect?