Good for Mr Mack, it's well deserved.
I think you're missing the point JD, I wasn't doubting the popularity of the Trek Fiction line, as I assume others weren't either. The books are still being wrote, money is still (probably just about) being made on their sales which proves there is some popularity about them.
What I highlighted and others have commented on, is that it's seemingly less common to buy a Trek book from a bricks and mortar shop. I myself "picked up" all three Cold Equations from the Book Depository and it would be interesting to discover what the percentage of sales are at the moment regarding internet sales vs brick and mortar sales.
As a side, that NYT bestsellers list, does that just include sales from North America or does it take global sales into account?