This was what happened in the past(Source: Bob Buford, My Next Book Year 5):
Church historian Rodney Stark reports between 1960 and 2000, the Episcopal Church declined 55% in terms of members per 1,000 U.S. population. The United Methodist Church declined 49%, and the Presbyterian Church (USA) declined 49%. Megachurches have doubled in number and size in the past five years. This leaves the churched population among Christians at about 40% attending regularly. It also says, with about 85% nominally Christian in the U.S., only about half of them regularly attend church. They are not unChristian; they are unchurched.
These are currently the largest and fastest growing churches in the USA (Source: Outreach Magazine 09/09):
LARGEST (church name; location; pastor; attendance)
1. Lakewood Church; Houston, TX; Joel Osteen; 43,500
2. LifeChurch.tv; Edmond, OK; Craig Groeschel; 26,776
3. Willow Creek Community Church; South Barrington, IL; Bill Hybels; 23,400
4. North Point Community Church; Alpharetta, GA; Andy Stanley; 23,377
5. Second Baptist Church; Houston, TX; Ed Young, Sr.; 22,723FASTEST-GROWING (church name; location; pastor; attendance growth by number; percentage growth)
1. New Life Church; Conway, AR; Rick Bezet; growth: 2,200; 61%
2. Calvary Temple Worship Center; Modesto, CA; Glen Berteau; growth: 3,180; 43%
3. Cornerstone Church of San Diego; National City, CA; Sergio De La Mora; growth: 1,439; 59%
4. Elevation Church; Charlotte, NC; Steven Furtick; growth: 1,598; 44%
5. Faith Church of St. Louis; Fenton, MO; David Crank; growth: 1,138; 102%
And here is a snapshot of the house church. Is this the future? (Source: Barna update 30/09/09)
Barna Research asked survey respondents about house churches by defining them as, “part of a group of believers that meets regularly in a home or place other than a church building. These groups are not part of a typical church; they meet independently, are self-governed and consider themselves to be a complete church on their own. Do you participate in such a group, sometimes known as a house church or simple church, that is not associated in any way with a local, congregational type of church?” The response to this inquiry consistently generates just 3% to 6% of all adults saying they have been involved in such an assembly during a typical month. Broader definitions of a house church generated “yes” answers from up to 33% of respondents. Barna Research reported in 2006 that 1 in 5 adults attend house churches. A follow-up study by Center for Missional Research commissioned a Zogby study that asked. “Do you meet weekly with a group of 20 people or less to pray and study Scriptures as your primary form of spiritual or religious gathering?” 26.3% of the 3,600 Americans polled answered “yes”.