A320neo vs. B737MAX market share

At last week's PNAA conference there was one more time the may be never-ending discussion about how Airbus and Boeing will split their market share in the narrowbody market (there is no talk about how Bombardier will be doing with the CSeries, but this is would be a complete different - and at the moment quite sad - story).
This discussion was initiated by Richard Aboulafia, who predicted a 60% market share for the A320neo. Boeing's VP Marketing Randy Tinseth soon dismissed that, saying that he believes Boeing will have a 50% market share with the B737MAX (and he would do a bad job if he would not do so, of course).