Backlinks will likely always be ONE of the many criteria google uses. Google will never tell what all the criteria are. All we know is that it’s in excess of 99 different ones.
Also, Google is getting smarter and smarter about locating link exchanges and paid links, and it is a primary focus. Google likes NATURAL links, and they mean to sort this.
I also agree with Simmo, google will look more and more at visitor behavior. I guess instead of spending time and money on links people will then try to game google by obtaining people to visit in certain patterns.
Search is really in it’s infancy, we will witness many changes as we go. There is no such thing as sure fire SEO, what holds true today will be changed tomorrow.