But that is the point.....our current (and past for almost 100 years) can no longer sustain themselves.  Some well-known orders have already "collapsed" by folding their few remaining members into other, related congregations.  As for being "attractive," by which I assume you mean creating interest in the affiliate groups, my sense is that it is already happening with those orders creative enough, and committed enough, to creating that future for themselves.  An outstanding example, in my mind, are the Marianists (Society of Mary) who have various types of related groups, some of whom make "Promises" to the community, some belong to a Sodality based on the structure of the original congregation, and so on.  You may want to check them out.  Where there is a will, there is always a way.  It is useful to look at it in reverse: what is it now that keeps many Catholic away from our doors?  If we listen to the answers, the way forward is clearer.