I have some speculations of my own.
The Beatles. They started out as "pop trash" too, right? I've only figured this out recently, mostly because I never like their earlier music when I listen to it. It's what they were. "Guitar bands are on their way out." So, they spend a few years like that, and get to unimaginable levels of pop stardom. Girls screamed over them like they scream over, hey, Justin Bieber. Then what happened? They started to make ART. Not POP.
Although, I will say the current batch of tweens has musical ADD, unable to concentrate on one band for more than eight seconds.
But, let's say they like Bieber enough to support him until even he starts to get bored of auto-tune. What then? If he does have any talent, he'll find a new label, new songwriter (Because we all know he sucks at it), new producer, and a new image. Maybe go on a soul-search in Nepal, I don't know. And then he comes back- BAM!
ART. Not POP. Hey, it happens with all sorts of classic rock bands. You just don't see all the criticism of their pop-ier songs, or at least, not the bad criticism. Criticism as bad as what we give to Bieber.
If that type of thing happens with any artist, my money's more on Lady Gaga. She actually had a little bit of singing talent in the first place. Maybe if she can revert herself back to piano-playing local-American Idol-auditioning former persona than she can start making some actual good music.