What should an income poverty target look like post-2015?

It is clear that the world has changed a great deal since 2000 when the MDG framework was finalised. Extreme poverty has declined while more poor people today reside in middle income rather than low income countries. What this means for the post-2015 development framework is currently under intense discussion.  In this one off event Martin Ravallion, Director of the Development Research Group at the World Bank  asks “What should an income poverty target look like post-2015”?