Amongst Lindsey Lohan, Paris Hilton, Britney Spears, and Jessica Simpson, I'm taking odds:

In 15 years, who is most likely to still be successful?
In 15 years, who is most likely to still be attractive?
In 15 years, who is most likely to be dead/done/Courtney Love?

Successful:
Simpson 3-2
Lohan 4-1
Spears 6-1
Hilton (Never has been successful)
Lohan is determined to be Courtney Love at best, Spears is, much like Christ Eliot, surviving on pity at this point, and Hilton isn't even very good at being a felon. Simpson by default. Plus she's soulless, she seems like she'd take up ska if it made her money. I can picture being like SNL - it makes too much money to cancel.

Attractive:
Lohan 3-1
Simpson 3-1
Hilton 4-1
Spears 30-1
I'm torn, Jessica's prettiest now, but Lohan should age better if she's not torn up by the steady booze/drugs diet. Hilton is not currently attractive, but she's legit skinny and should age well. Britney's waging war w/ her Elvis pounds; it's a matter of time.

Done/Dead/Courtney Love:
Lohan 5-4
Spears 3-2
Hilton 2-1
Simpson 4-1
Lohan behaves as though she already made this bet on herself. That and she doesn't understand the bet and thinks she's in the hole if she doesn't get there fast enough. I can't see how Spears could hold it together another decade with the pounds on their way. I don't know how Hilton could keep herself in the news without actually doing anything. Simpson has two ways to get here: 1) she just gets enough money that she doesn't need to stay in the game, or 2) she randomly has a complete breakdown.

Incidentally, Tara Reid tried to get in on this bet but didn't make the cut:
http://www.youtube.com/watch?v=q3bRrKqo2jQ