Alan Hirsch has written an excellent post on the challenges of helping an established church to become more missional.
The issue of change and transition into missional forms of church is fraught with many complex problems. But again, at the heart of the problem is our ‘idea of church’—the conception we have of what it means to be God’s people as a community. Part of the problem is that we have so associated our idea of church with the institutional forms of it (including programs, services, professionalization of ministry, theologies, denominational templates, etc.) that we need to at least be given the chance to experience each other as Jesus’ church divorced from the predominance of the institution of the church.
You should note that when Alan says established church, he is referring to a church congregation that has been around for a long time – he’s not talking about an established church such as the C of E in England.
Let me, once again, recommend the book The Shaping of Things to Come: Innovation and Mission for the 21st Century Church which Alan co-authored. I don’t know how many times I’ve mentioned this book, but it’s a lot. But then again, I think it’s the most important book I’ve read in the last five years.