The future of the EU is in question, and not just because of Brexit, which is just one of the many crises that has hit the EU in recent years, including the Eurozone, refugee, and security crises. But how Brexit occurs may have a significant impact on future European integration, just as the future of EU integration will have an impact on UK engagement with the EU. This chapter begins with the UK’s reasons for exit and its history of opting out of EU policies before considering the many crises challenging the EU, including Brexit. It then discusses the current already highly differentiated state of the EU, followed by the likely future of even greater differentiation. The chapter argues that only by conceiving of the future EU as consisting of a ‘soft’ rather than hard core with different clusters of members in overlapping policy communities is the UK likely to be able continue to have a productive relationship with the EU through some of its various policy communities, or is the EU itself most likely to move forward in a positive direction.