I think I may have to disagree with both of you.
99X went downhill when it was taken over by Cumulus and the playlist became generic. Alternative in the early 2k's went in a harder direction. In fact, the harder direction started in the late 90s with Marilyn Manson and Tool which were first heard on Alternative stations. First time I ever heard of Type O Negative was on 99x back in the day. Type O was a doom metal goth band. In the early and mid 2ks, alternative charts went more in the pissed off skater boy bands like Three Days Grace and Hoobostank. In 2003, billboard charts has Saliva's Always at number two. Fact is, commercial alt stations were leaning harder because the charts were going in that direction and with the popularity of harder rock, active rock stations were booming and you had AAA stations for the softer alt pop music (Dave FM). So in Atlanta, you had harder active rock on The Buzz (later Project) and AAA on Dave FM. 99X no longer had an identity.
When 99X reemerged in the late 2k's, they were incredibly "safe". I remember them airing M83's first hit about three months after other big city alt stations were playing it. Under Axel, 99X did start adding in 90s metal like White Zombie which in the 90s, was being played on alt stations. Again, no identity with a AAA station (big stick) covering the college rock and adult alternative rock and project playing the harder rock.
Today, Alternative is sorta back at it's early 90s roots or dare I say late 80s. Lots of synth pop and folk.
Personally, I like the new 99X and think they have a good idea. I don't think it would work though because it's still a commercial radio station. Alternative, true alternative music, should be left to college radio.
I'm not a fan of active rock BUT I think some active rock would work in Atlanta. Ideally, an active/alternative hybrid much like 1057 The Point in St. Louis which leans alternative but isn't afraid to play Disturbed either. Project got old because they would play Disturbed and a few other popular active rock acts every hour. I would think an active/alternative hybrid would widen the playlist enough to where it wouldn't get old.