It already is a reality. If you want to divorce content completely from presentation, you can do that right now, today, with HTML & CSS. There's no technical hurdle stopping you.

The problem is that understanding that "content" and "presentation" are two separate things requires people to work at a level of abstraction that most of them are not used to working at. In the tools they're familiar with, it's all mashed together. (You can separate the two in Word with things like document styles, but that's not how Word works by default; and there's little practical benefit to doing so for small documents anyway, so few people discover it unless a more advanced user takes the time to teach them.) So when you try to teach them to do their work in this new way, it feels to them like you're just adding unnecessary complications to their workflow. They then reject your tools as pointless egghead stuff, and you for trying to foist them on them.

It's a cultural problem, in other words, not a technical problem.