That's funny, when I read that in the newsletter I read it as free for all. Didn't think of it as enabled on all cards but you would need to pay if not Gold or Platinum but you are most probably correct.
You are correct. Complimentary egate for all skywards members irrespective of tier as per the august newsletter. I don't know if its a typo as DXB is going to lose a lot of money if this is the case as a significant number of pax flying to DXB use EK anyway.
The exact wording is
With complimentary e-gate now available on all Emirates Skywards membership cards, for eligible nationalities, you can enjoy a more convenient travel experience at Dubai International Airport.