If you can afford it, you leave. That's the natural thing to do. I don't know of any church that has developed a program to help their urban people be willing to move to the suburbs. Such programs are not necessary. Almost all the natural gravity pulls in that direction.
Downward mobility is un- American.
Therefore, I take as part of my calling in this church to so preach and to so live as to persuade some Christians to move to the city to spread a passion of the supremacy of God in all things. In short the church doesn't need as much help to spread itself as salt through the suburbs as it does to spread itself as salt through the decaying inner city. And it is calling for the suburban folks to glory in their appointed ministry and not to resent the necessary focus and effort to swim against the tide to help people survive in the city. I hope that Bethlehem will be a place where more and more suburban people are saved and love to be a part of a church that is committed to the city, while staying right where God calls them. The second thing to see in this text is that what holds the range of diversity together in the church is the supremacy of Christ.