I don't see how EMDs can lose their value.
For every one internet-savvy IMer on BHW, there must be 10 people who have absolutely no tech/web knowledge whatsoever. You know the type of person: if you recommend them to use Firefox instead of IE, they say "oh no that sounds far too technical".
I run a forum where a large proportion of the members are like that. They need a lot of hand-holding from the mods, because changing a sig or avatar is a major feat for them.
Anyway, I know that most of these people don't even use the browser's address bar, or bookmarks, to find the site. Even those who visit the site every day start up their browser, see the search box on the home page, and type the site name (ie, the url) into the Google box. Of course then the site they want is top of the search results, so they just click that and thus get where they want to go.
I've spoken to quite a few people from outside that forum too, and they're the same. Christ, I've got family members who think that their web browser is called "Google" (and it's not Chrome, it's IE - they just think that because when they start it they see the word "Google")
I think that although it's easy for people like BHWers to forget, there are lots of people who navigate the web using search engines in this way, even when they know the url, and you can bet that G knows it.
Devaluing EMDs would leave all these people completely stranded. So they can't do it. IMHO.