I think what McLuhan means when he talks about there being “no detachment” is that media nowadays are much more immersing. For example, when McLuhan talks about forced perspective in Renaissance art, he is talking about immersion. Forced perspective is different from prior art because it makes the user feel like they’re actually present at the site of the painting. Prior works simply showed what was happening, but forced perspective portrayed what the viewer would see if they were actually there in person.
Modern video game user interfaces (UIs) have also taken a similar approach. I recently played through the Mass Effect series, and the game’s UI is futuristic, with radial menus, sci-fi-esque typefaces, and bright color palettes (orange and neon blue to be precise). All the UI elements are made to match other parts of the game: the colors in the interface are the same as the ones used for holograms, displays and even the character’s “omni-tool”. All this leads to a more immersing experience, where what the user sees is similar to the in-game art.
Minecraft is another game that uses UI elements to make the experience more immersing. Inspired by the game’s blocky, pixel-art style, in game text, menus, and buttons try to emulate the art style of the game, and therefore create an experience where the UI is not simply layered over the game, but actually feels like part of it.
In general, I agree with McLuhan’s assertions that we are becoming more and more involved in what is happening in the world, and that there is more shared sentiment (for example, on page 61 when he talks about an event where someone “says ‘how horrible it must be to feel like that” instead of blaming someone else. I think McLuhan’s thought that we are entering an age of “total involvement”(61) is spot-on.
DTC 375: Jesse Pearson 
I think the modern GUI for video games makes us much more amerced in technology than ever before. These games now can make you feel as if you are actually a part of the action happening. I notice my self jumping a lot at random points if someone comes around a corner and I’m not expecting it. The more interesting the game is the more captivated I get as well.