The problem with the Braves offense isn't that they might or might not be able to adequately replace Jones, but that the patches they'll employ to cover for their being less Chipper can't be used to fix the other leaks in the lineup.
Does that mean they have to make a trade? Not necessarily, because they can reacquire that depth down the stretch if they do as they've done in the past, and turn to the top almost-ready talent they've developed themselves. A Freddie Freeman call-up would involve accelerating the timetable for the 20-year-old, but over in Gwinnett the kid has hit .319/.384/.531 against right-handers overall, and has pasted everybody at a .371/.427/.603 pace in 131 PAs since the All-Star break. He doesn't have to be next Andruw Jones or Chipper Jones for the Braves to simply keep up ahead of the Joneses. Nor does it have to involve moving Glaus to third base as an everyday player—it's about getting offense period, not just finding a third baseman.
In that light, describing turning to Freeman as a “risk” in light of their reliance on Heyward strikes me as particularly silly—an aging, slumping Glaus is no more of a sure thing, having been something of an accepted risk with placeholding potential from the moment Frank Wren signed him. Glaus was supposed to keep the seat warm from the get-go, and if Freeman's bat is already re-setting the timetable for his arrival, that doesn't need reference to Chipper Jones' situation, but Jones' absence certainly eats into Wren's ability to let it ride with Glaus for much longer.
Kahrl also identifies Jose Lopez, Chone Figgins, and Mark Reynolds as expensive players on bad teams who would represent an upgrade for the Braves at third. I suspect that Frank Wren is not going to take on any of those salaries unless he knows that Chipper isn't coming back next year. Kahrl suggests that the Braves would be able to move one of those guys in the event that Chipper does come back, but after the Rafael Soriano experience this summer, I doubt that Wren is going to allow himself to get into a position where he has to trade an expensive asset.