Well, the Foo Fighters did release Wasting Light in 2011 (which I own, it's quite good). Rope was just hard enough for my Rocker friends to really like it, but then it was mainstream enough for my Pop friends to really enjoy it too.
I also heard a rumor somewhere that Dave Grohl was approached for a Foo Fighters Episode on Glee. Now, if Dave did say yes (which would require a different set of mind, it would alienate a lot of his old fans methinks.....) then the Foo Fighters Songs would get into the mainstream again. Glee did manage to get "Forget You" into the charts, after being near the bottom at its debut.
What about The White Stripes? I know they broke up, but could one of Jack White's side bands go a bit further? He and Alicia Keys did do the Quantum of Solace song, which seems to be a hit or miss with people.
Maybe make The Strokes a bit more popular?
A further back solution would be for "Rock" to transform the way it did.
Rap and Pop seem to really be hitting that point where the record companies are controlling everything, and there's a strong "counter" culture to it.
Rock went through that in the 80's with glam metal right? A good example of that is "We Built This City" by Starship if I'm correct.
That directly led into Grunge, as Grunge was the counter to over-commercialized Glam Metal from what I understand.
Grunge was associated with the darker bits of society, which lead to Emo, and the Emo collapse.
After about 2005 Rock is more of an Counter Culture movement.
Then, all this could easily be my ignorance of the situation. So take this with a grain of salt, but I think that for Rock to stay a pivotal form of music (as Rock was always there when a decade's pop music popped up, disco, 80's pop, Boy bands, etc.....) you would need to change how Rock was in the 80's. Other than that, you would need Bands to try and distance themselves from the stigma that Emo has, whether they try to go Pop-Punk again, or make an entirely new sound is up to them.
Again, these are just ideas popping into my head, sorry if they aren't all there.