Right now, per the best estimates available, the Atlanta Falcons have between $14 and $16 million in cap space. That's a decent chunk of change, most of which is likely ticketed to contingencies and a Julio Jones extension. It's a boring thing to say, but I doubt we'll see any other major signings between now and the season.
The calculus changes if you think there are worthy free agents available to patch needs, and depending on the stringency of your definition, there may well be. Jermaine Gresham is available and drawing interest from the Saints and other teams at tight end, while Evan Mathis is improbably out on the open market despite being easily the best lineman available. If the Falcons think they'll have enough cash even with Julio's new deal, there are options for them to pursue.
Personally, I'd advocate pretty strongly for Mathis on a two-year deal. He's getting older and you don't want to lock him down for years if he's going to be declining, but if it's remotely possible to sign him to a shorter accord, he's such a huge upgrade for the offensive line that it's basically a no-brainer. Gresham isn't a huge upgrade over what the team already has, especially coming off of injury, and there's nobody out there right now beyond those two that warrants an immediate signing to these eyes.
It's also true that the risk of carrying a goodly amount of cap space into the season is that if you don't use it and the team flounders, fans will be blind with rage that you didn't spend the money on upgrades. That attitude can be off-base, particularly in what promises to be a little bit of a transition year, but I do think it's defensible this year given the team's real holes at a handful of positions. If you can spend a little to help yourself a lot, you should do so.
Ultimately, I expect the Falcons to land a couple of cut players in late August and to extend Julio Jones, which should eat up most of that available space. Don't be surprised if there's around $3-$5 million in remaining space for that infamous rainy day fund, and to use toward next year's cap. It's not sexy, but if the team can play well this year and position itself to raid the open market for 2016, I doubt many of us will care. If they don't, we'll grouse like hell, I imagine.