Nuptial Cohabitors?

Two researchers and writers from a Catholic university recently published an article in US Catholic that provoked a lot of comments. The authors were attempting to find a pastoral way to deal with the reality that fewer Catholics are going through with sacramental marriage and also that a significant number of those couples who do approach the Church for marriage preparation are already "cohabiting." The authors make a distinction regarding cohabitation between those who are already mutually committed in some way and so are "nuptial cohabitors" and those who have no intention of marriage (non-nuptial cohabitors). Their proposal involves a way to remove the stigma of "living in sin" from those who live together prior to their marriage. Their proposal involves a restoration of the period of betrothal to marriage:
Our pastoral proposal is straightforward: a return to the marital sequence of betrothal (with appropriate ritual to ensure community involvement), sexual intercourse, possible fertility, then ritual wedding to acknowledge and mark the consummation of both valid marriage and sacrament.
Since these couples will have already initiated their marriage through betrothal, their intercourse would not be premarital but marital, as it was in the pre-Tridentine Catholic Church. We envision a marital process initiated by mutual commitment and consent lived in love, justice, equality, intimacy, and fulfillment in a nuptial cohabitation pointed to a wedding that consummates the process of becoming married in a public manner. Such a process would meet the legitimate Catholic and social requirement that the sexual act must take place only within a stable relationship.
The process would be: Betrothal: The couple’s betrothal, which would involve a public ritual highlighting free consent to wed in the future, would be witnessed and blessed on behalf of the church community. The betrothal ritual would differ from the present wedding ceremony in that the consent would be to marry in the future. Such betrothal, as it did in earlier Catholic tradition, would confer on the couple the status of committed spouses with all the rights that the church grants to spouses, including the right to sexual intercourse.
Nuptial cohabitation: During this period the couple would live together as spouses, enjoying the approval and support of the community, and continuing the lifelong process of establishing their marital relationship as one of love, justice, equality, intimacy, and mutual flourishing. During this time the church would assist the couple with ongoing marriage education aimed precisely at clarifying and deepening their relationship.
Finally, sacramental marriage would be a celebration of the committed relationship that exists and a commitment to further growth.

The authors were severely criticized for their proposal. The bishop of the diocese where they teach wrote a public condemnation of the proposal in question. The fear behind the criticisms apparently being that the proposal is simply finding a way to condone behavior that has long been considered immoral by the Church.

In the RCIA blogs which I read from time to time I regularly find discussions of the problems of dealing with these "nuptial cohabitors". I suspect that this matter is dealt with in a wide variety of ways from not dealing with it at all to insisting that the couple spend a period of time apart before the wedding. Would reintroducing the idea of betrothal (commitment to marry in the future) be a way of regularizing this increasingly common form of living arrangement? Would any of the couples who are "nuptial cohabitors" care? In the long run would accepting the author's proposal have any impact on the long standing Church teaching regarding the role of sexual intimacy in a relationship? These would be interesting questions to explore but I suspect the volume of criticism that this proposal generated means that such a proposal in not about to be considered any time in the future.