Having dealt with Wordpress a handful of times in the past, I can see where is this post coming from.
"Wordpress will die" as in, most sites will eventually graduate out of Wordpress. Many sites start out with it because it's easy to get started, and if the site's needs grow, then WP will quickly tax you a very expensive technical debt.
All the code written as plug ins is extremely WP specific, has to be PHP (which isn't coolest - personal preference), and the general WP architecture always felt quite unnatural to me. That will make it changing out of WP, an expensive rewrite.
I remember hearing in podcasts, that there is an important rewrite of WP to split the admin and make the backend behave like an API, which sounded great IMO.
The problem remains when wanting to use WP as the main website engine, I think it's great for a blog that you won't have to touch much, but not for your core site (unless it is a blog).