Lisa Belkin, who writes the Motherlode blog, has a short piece in the New York Times Magazine about the changing meaning of "wife."
She notes that her mother, a divorced feminist who switched from teaching to lawyering, rejects being a wife. Belkin is a highly invested wife and mother, trying not to be too much of a helicopter parent. She thinks that the next generation of women won't know what to do with the wife role because it will be too indefinite, have too many possible meanings. She thinks the crucial change is that the men who young women marry are taking on more of the house roles, especially the parenting roles, that wives and mothers used to do almost exclusively.
I think Belkin is right that the key to changing the wife role comes from husbands taking on more of the kid-raising. Belkin also notes, though does not emphasize as a cause, that wives bring home almost half the family income among young marrieds, and a fifth of young wives make more than their husbands. I believe this latter fact is the other half of the equation of re-jiggering husband and wife roles.
On the other hand, biology will continue to make women into mothers in powerful ways. That will be the starting point for the great majority of married couples' role negotiations. I believe that the Millennial generation will differ most from the '70s feminism of their grandmothers in seeing that the crucial part of marriage is not primarily about the identity of husband and wife as individuals, but as a partnership to raise children.