The state of the 800 with Brother Colm

Brother Colm Oconnor has coached the last two world record holders in the 800. The 800 has had one of the lowest number of WR's in an event. Why did David break it and will we ever see sub 1:40? Since 1979 there have only been three men to hold the record. 1:42.4 1:42.33 Sebastian Coe (GBR) 1979-07-05 Oslo, Norway[1] 1:41.73 Sebastian Coe (GBR) 1981-06-10 Florence, Italy[1] 1:41.73 Wilson Kipketer (DEN) 1997-07-07 Stockholm, Sweden[1] 1:41.24 Wilson Kipketer (DEN) 1997-08-13 Zürich, Switzerland[1] 1:41.11 Wilson Kipketer (DEN) 1997-08-24 Cologne, Germany[1] 1:41.09 David Rudisha (KEN) 2010-08-22 Berlin, Germany[2] 1:41.01 David Rudisha (KEN) 2010-08-29 Rieti, Italy[2] 1:40.91 David Rudisha (KEN) 2012-08-09 London, United Kingdom[3]