Google updated their ranking algorithm over 400 times last year according to Matt Cutts, Google Product Manager for WebSpam.  Google is already moving in the direction that the article is discussing somewhat, but rather than just focussing on the true "Semantic Web", I believe that they are working on a "social layer" to the web that analyzes what other people (specifically your friends and associates, your trusted social circle) recommend, look at, and like.

Think about it this way.  How often, when you have a question, do you go to Facebook and/or Twitter and pose it to the masses for an answer?  How often is that answer quick, and really really good?  It is the equivilent of calling up your nerdy nephew when you want to know what kind of Digital Camera of computer to buy, or when he calls you and asks you what the difference between a Roth IRA and a traditional IRA are.  We all have expertise, hobbies, and skills and Google becomes less and less useful if Facebook or Twitter allows you to get relevant quality information from people that you trust about topics that you are interested in.

That is the thing that Google fears more than anything else, and that is direction that I think that they are moving in.  And one of the reasons why Public (Toolbar) Page Rank is going away.