Dwight Freeney is visiting with the Falcons this coming week, and if you think Freeney can still be an asset as a pass rusher (spoiler: he can be), then you'll be excited about that. If Atlanta actually goes through with signing him, though, it certainly complicates the depth chart.
It's already complicated, because we don't know exactly who the Falcons are keeping at linebacker and defensive end, but a healthy Freeney certainly pushes someone else off the roster entirely. If you consider his role at this stage of his career, it's likely as a defensive end who plays some linebacker for Dan Quinn's defense, and primarily on third downs and in obvious passing situations when he can do what he's done better than most defenders over the last decade. That means that someone like Tyler Starr, who is being developed as a potential pass rusher, could find himself without a spot, if he's not already without one.
If you're thinking Starr's already gone, you might be looking at a Sean Weatherspoon or Philip Wheeler a player who would likely have a Freeney-esque role if they don't wind up as a starting linebacker. The Falcons could also consider cutting ties with Courtney Upshaw, though he has a very different role than Freeney, if they think they've got enough run-stopping prowess already on the roster. Ultimately, I think it'd be one of those four players or so, but there are so many unsettled roles on the roster it's just a best guess.
Ultimately, it's not easy to figure out who would be losing a spot to Freeney, but my best guess would be one of the guys mentioned above. Given that Freeney can still bring pass rush to the table as his career winds down, though, I think he's a worthwhile addition.