The main proposition of Liza Mundy's new book "The Richer Sex," excerpted in TIME this week and on sale March 20, is that women will ultimately become the primary earners in a majority of American households -- and that this will profoundly affect personal relationships between men and women, including their sex lives.

Mundy introduces her discussion of this mini sexual revolution (discussed in a chapter called "Sex and the Self-Sufficient Girl") by challenging the enduring notions that men want sex more than women and that women have sex to secure men's commitment. She argues that the "Big Shift," as she calls the transition to women becoming the breadwinners in most households, makes it clearer than ever that these dated notions are all wrong.

Here are just a few Mundy's predictions for our sexual future. For more, pick up a copy of "The Richer Sex."

SLIDESHOW: 6 Ways Your Sex Life Is About To Change -- Or Already Has

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  • Women Will Want Sex More Than Men

    "Women are becoming the gender that wants sex more than men do," Mundy argues. She writes that women's professional success has "unleashed" them sexually, leading them to seek sex more directly and to be open to a greater variety of sexual experience.

  • Women Will Be Less Interested In Commitment

    The best proof of this, Mundy says, is that so many of the women she interviewed can't find men worth committing to. "If sex, for women, were about nothing more than securing commitment, at present there would be very little sex going on, because there are relatively few men worth committing to." Most of the women she talked to, she writes, "wanted to delay commitment. And the could. They didn't have to get married right away because they didn't need a provider."

  • Men Will Be More Likely To Withhold Sex

    Mundy argues that men whose wives and girlfriends out-earned them are less interested in sex with those women, for a variety of possible reasons, including a loss of intimacy caused by the man's resentment or sexual dysfunction that results from feeling inferior. The consequence, Mundy says, is that, "Just as women are said to do, men in some cases withheld sex, strategically, as a way of exerting what power they felt they still had."

  • Women Will Have Sex With As Many Men As Possible

    Mundy writes that the younger women she interviewed were having a lot of sex, "for the purpose of maximum exploration." In general the women she interviewed were having sex "because they enjoyed it; because it was available; and because -- far from being anxious to commit to one man, they wanted to have sex with as many men as they could, to see who was best at it ... One woman actually referred to this as 'test-driving a lot of cars before you buy one,'" she reports.

  • Women Will Be More Critical Of Men's Appearances

    "Women are responding to their wealth and independence by getting pickier about the appearance of the men they have sex with. The old wealth-beauty tradeoff may be reversing: Increasingly men may be the ones offering beauty -- and sexual service -- in return for the economic security women offer," Mundy writes.

  • Women Will Refuse To Change Their Own Appearances For Men

    Mundy writes that many of the women she talked to were well-groomed but "united in the feeling that, as the entrepreneur put it, 'this is as good as it gets.' If a lover requested modification, they felt free to decline."