From Wikipedia:

Well-known bestseller lists in the U.S. are published by Publishers Weekly, USA Today, The New York Times and The Washington Post. Most of these lists track book sales from national and independent bookstores, as well as sales from major internet retailers such as Amazon.com and Barnes & Noble

If the book I author appears in Publishers weekly, NYT, Washington Post or USA today as a bestselling book, before the close date, then this market resolves yes.

If all of these lists cease to exist, then resolves N/A. if any of them still operate, then they count.