I think it's a tough question to answer. Just because you can publish to thousands should you?
I teach my students the core skills they need. How to navigate a program, to be able to teach themselves a new one on their own. I teach them the basics of creating, editing, and formatting. I teach them the basics of the internet, how to get places and how to figure out what they want, how to get it and why they can't get where they want if they encounter a problem.
I then leave it up to them to decide how they want to use that knowledge outside. I fell as educators we need to give them the basic skills so they can publish to thousands, if they want to. But what about the technologically advanced student who doesn't want the world to know? I challenge them too, knowing it is ok to create for oneself.
I think the key, or main concern, needs to be teaching them the core skills. Having the basics will allow them to decide how they want to the world to see them in this digital age. Knowing how to blog and blogging are two vastly different things. Just because someone can put words on a blog doesn't mean they are "prepared for the 21st century". Just as the absence of a blog doesn't mean they aren't prepared.
To me preparation is about exactly that, preparing the skills. I prepare them. I leave the execution to them.