It's been a long time since I watched anything more than clips of the show, but Jon Oliver seems like the ideal successor host. The issue with that is that he has Last Week Tonight, which may actually be a better format for the media of today given its stronger and more unique segments, and the fact that people under the age of 60 are shifting away from scheduled TV at a very fast rate.
http://www.bbc.com/news/world-us-canada-31396423
http://www.bbc.com/news/world-us-canada-31396423
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