When will robots triumph over world cup winners? Why will it take that long?

A recent IEEE Spectrum article asked  Will Robots Triumph over World Cup Winners by 2050? and talked about many subtleties of that challenge. 
IMHO This is a very formidable challenge for robotics, 2050 is a very long way into the future, and the date when robots will triumph is topic for expert conjecture.  When do you think robots will first triumph over world cup winners?