Hear my thoughts on this - I wanted to hear others before I give my own thoughts.
Go to bilboard and look back at the alternative charts in the early and mid 90s. This would have been when alt was POPular and many artist were on top 40 stations. The music was more poppier with an edge and less rock.
Then skip over to the early 2ks. You had bands like Unwritten Law, Chevelle, Taking Back Sunday; You had these clean cut skater boys playing post grunge and post punk music. It was very "rocky" shall we say. During this time, we also had active rock stations that were playing the same thing plus more. These bands don't make it to top 40 radio. Alternative lost.
Then skip over to 2012 and you had Fun, Gotye, Imagine Dragons - These were yet again more poppier styles (similar to early 90s) and they made it to top 40 radio due to their POPularity. This got the brand of alternative out - hints the explosion of alternative.
Now when and where will alternative head?
Many of you know clear channel uses premium choice satellite feeds for many stations. I'm keeping the name anonymous but I spoke with someone over there who said that this time last year, most alt stations (that they had) were on prem choice except radio 104.5. Now it's all the active rock stations that are on prem choice.
I will also say this - Phones are ringing off the hook at alternative stations because their music has gotten too poppy for many even alternative fans. It's almost as if radio is forcing a more pop sound to alternative.