A proposition thrown out there for myself and anyone who would critique it. In today's celebrity youth culture almost all celebrity is bought on credit. One finds fame by
1) manifesting the epoch's own perceived image of its Zeitgeist, or
2) going to the extremes of this perceived image, or
3) selling oneself by virtue of a loan--a star provides his or her youth (or equivalent) to the machine, in exchange for fame. But there are two kinds of fame, the temporary and the durable. The grant of the former leads only to a chance at the latter. The machine enables the star-to-be to apply for durable status by means of a "trial period." If the investment provides no returns, the star is discarded along with her youth. In the case of someone like Britney Spears (who may yet pull off a comeback or two in her lifetime, who knows), her initial investment was so much that the machine can feed productively off of her unraveling as she struggles--unsuccessfully, it seems--for durability. Her increasing lack of success is at the same time the machine's energy source, and its manifestations about her (and her success, and lack of it) are strengthened by it. Or, at least, they are shown to be strong by it. They produce, for example, figures who fit into categories 1 and 2, like Chris Crocker. I first suggested an idea in this area in the very first film blog-a-thon. Elizabeth Berkley was a victim of category 3 but has a resurrected phantom career on the current popular surge that enables a surplus of category 1 (as well as 2)--hence she gets the hosting gig for the dance show on TV, because she is "visible" in pop culture precisely as a revenant from that early burnout, the failed attempt at a smooth path into respectable star longevity. Neil Patrick Harris did the same 3-to-1 move to rather hilarious effect with Harold & Kumar (I haven't seen his sitcom), which may have been first forged in his collaboration with Verhoeven in Starship Troopers.
I give Miley Cyrus a few more years. I don't say she'll be forgotten, but she'll be faltering and will have to manifest herself as a figure of category 1, probably, running of the fuel of her cat-3 burnout.
"I have begun to work again, and am making good progress. Only, I have to limit my working time, for after about three hours my head begins to hum and feel painful."
- Marx to Engels, April 22, 1868