If i say "find me a good ticket for Chicago tonight". How 
  will it know that i'm talking about the rock band that's 
  playing tonight in Paris, France, since there's absolutely 
  not a chance that a human being asks for a plane ticket for 
  such a big trip just a few hours in advance ?

I don't even need an assistant system to figure out based on context which I'm talking about: All I want is one that can simply ask clarifying questions. "Did you mean Chicago the city, or Chicago the band?"

I had an amusing Siri interaction a few months ago where I asked "what language is spoken in Shanghai?" (I can never remember if it's Mandarin or Cantonese). Siri came back with a very well-reasoned, completely out-of-place answer of "Hindi": https://twitter.com/claymill/status/690386752683577344