Should Indy Car Racing abandon open cockpits?

Sunday's Indianapolis 500 was won by Takuma Sato of Japan who races full time for Andretti Autosport.  Winning the Indy 500 is an amazing accomplishment, however the most amazing thing that happened Sunday was driver Scott Dixon walking away from this crash.  

No driver was hurt in what was a 5 car pile up.  A feather in the cap of IndyCar racing, but remember the last two deaths in the IndyCar Series were the results of head injuries.  Dane Wheldon in 2011 when his car flew into a catch fence and his head hit a metal pole at Vegas Motor Speedway and Justin Wilson in 2015 when he was hit by debris from a wrecked car at Pocono.  As a result Indy Racing entertained the idea of enclosed cockpits, but nothing changed.

Watch the above video again, had the rotation of Dixon's car been a split second faster the roof would have landed on the top of the wall.  That means his helmet would have hit the concrete and mere physics plays this out badly.  The question is raised again, should IndyRacing create an enclosed cockpit for driver safety?  What do you think?