Very interesting. As a lark, some female friends of mine in high school looked into writing for Harlequin; it turns out they have a very elaborate "style guide" which has a built in morality code. No abortions, no actual cheating (hard as that is to believe), etc. etc.
What's interesting about Twilight is that is manages to hold essentially to these very traditional mores while still maintaining a "sexy" and "edgy" character. This is mainly due to subject matter- Vampires have always been a sexualized monster.
So if stephanie Meyer is off writing bodice rippers, I still think something a lot like Twilight would come along; there's been an effort to mainstream and make "cool" more traditional values (read: Christian) in the last few years by reconciling pop culture with social conservatism- especially sexual mores.
When you take this in combination with the highly sexualized American fixation with virginity, I think the 2000's is exactly the time for a virginal-but-sexy-but-lots-of-tension-but-elaborate-metaphor-for-purity fantasy tale aimed at young women. The question is; if not Meyer, then who, and if not vampires, then what?