I think the author is deluding themselves. They start by indicating what went wrong with Beasts and acknowledge that in large the failing was that it was not "Harry Potter". They then begrudgingly admit that the video game has been very successful. Couple that with the viral sensation that has been Hogwarts U or Hogwarts A&M on social media and one thing is abundantly clear. The Harry Potter Universe is still incredibly popular. The author seems to overlook that no one is suggesting a show based on Beasts. No, the show is going to based on the books. That is still very magical...and popular. Despite how some fans, many fan even, may feel about JK Rowling, millions haven't divorced themselves from the books choosing to embrace the books while opposing Rowling's position. The fact that Rowling has been unscathed by her remarks should be testament enough to the lasting powers of the book. But this author, like Hollywood, seems to struggle with the same concept that has doomed many book to screen projects; if the source material is beloved, don't stray from the source material. This series, if given the attention to detail and budget the books necessitate, will be a huge hit for WB and HBO. And the author, despite the existing proof that the fervor for the books is still there will be left scratching their head.
The following quote indicates just how little the author understands about the draw to Harry Potter: "While the 2001-2011 films drew mixed critical receptions, they had been embraced wholeheartedly by the Potter fanbase. It scarcely mattered that Radcliffe, Rupert Grint, and Emma Watson were stilted, dramatically uncompelling child actors. To the fans, they were Harry, Ron and Hermione." It never mattered how compelling the actors were (and don't get me wrong there were some standout performances by several actors throughout the series). It was always about immersion in a world that fans came to love. A TV series will just further that opportunity to relive it or experience it for the first time. The books are still as magical as they have ever been and I think will prove to be for a new generation of readers. Yes, recasting Severus Snape will be sad and hard to do based on the shoes Alan Rickman left to be filled. But like Sherlock Holmes, James Bond, and Romeo, Severus Snape can and will be played well by new people. The notion that literary interpretation should stop with the 2010s is absurd. The next Severus Snape will also have the benefit of knowing his characters full story arc. Of course, that doesn't guarantee a good performance but it gives the next actor character depth that the great Alan Rickman didn't have when he first took on the role.