What BMW doesn't see is that Tesla is gunning for the 3 Series market with the GenIII car. Tesla is confident they can make a substantially better car than the 3 series (or Lexus IS, Audi A4, etc) in most regards and make it priced competitively. I don't think BMW is taking Tesla seriously... they're more focused on existing competitors.
If Tesla succeeds in making a substantially better car than the 3 Series that's priced competitively, then everybody in that market (BMW 3 Series, Mercedes C, Lexus IS, Audi4, etc.) will be in catch up mode. And that will the story of the decade in the car industry... how a scrappy Silicon Valley startup did the impossible to the auto industry.