Don't see how this is different from ajax conceptually. It is mentioned that a single page application framework is required. While an SPA framework is preferred, everything seems pretty doable with JQuery, just not as nicely prescribed.
The item individualized custom placeholders I haven't seen as a standard pattern, but I'm not sure it's worth the effort.
I'm not sure you understand the point of this post? We're not talking about AJAX or an alternative to it. This has to do with page layout and design in conjunction with delayed asset loading, whether it's slow loading or AJAX.
I personally think placeholders/known sizes are a must in web design. It really annoys me when I'm reading something and it gets pushed down due to slow loading images, etc.
The item individualized custom placeholders I haven't seen as a standard pattern, but I'm not sure it's worth the effort.