Brian McLaren writes on the Patheos "Future of Mainline Protestantism" blog of his thoughts on the future of Christianity.
My general hunch is that in the short run, the most conservative streams of Christianity -- in Catholic, Protestant, and Orthodox settings alike -- will constrict, tighten up, batten the hatches, raise the boundary fences, demand greater doctrinal, political, and behavioral conformity, and monitor boundaries with increased vigilance. Doing so will increase commitment (and anxiety) among the "true believers," but it will also drive away their younger, more educated, and less isolated members.
While fearing that many will reject anything "church", McLaren hopes that those driven away will join an emerging coalition of organizations and networks that are "..developing both personal relationships and concrete plans for missional collaboration -- especially on behalf of the poor, peace, and the planet." He identifies four main religious sources:
Progressive Evangelicals who are squeezed out of constricting evangelical settings.
Progressive Roman Catholics (and Eastern Orthodox) who are squeezed out of their constricting settings.
Missional mainliners who are rediscovering their Christian faith more as a missional spiritual movement, and less as a revered and favored religious institution.
Social justice-oriented Pentecostals and Evangelicals -- from the minority churches in the West and from the majority churches of the global South, especially the second- and third-generation leaders who have the benefits of higher education.