The short answer to the above question is no, Google will never be able to eliminate spam. Plain and simple. No matter how good Google’s algorithms become, without human intervention to check and approve every single web page they index (something which is virtually impossible to do), they will never get rid of spam. Here’s why:

Computers Aren’t People

I really should qualify the above statement by saying that based on what I currently know and understand about computers, Google will never be able to eliminate spam. The reason is really simple: computers are not people. No matter how fast or well programmed a computer is, ultimately, it doesn’t “think” the way a human being thinks.
Even Watson, IBM’s Jeopary winning computer basically works by comparing millions of possible choices and then making the best guess. However, it’s still using a logical process to figure out what a question may be asking and this means it is not infallible. It doesn’t have the ability to discern certain things the way a human being can.

They Can Reduce Spam Greatly

Now that said, good algorithms can reduce the incidence of spam greatly. They can for example weed out spammy looking sentences, they can look for duplicate content across different websites and they can look for other telltale signs of a spammer. This is what Google relies on today not to inundate searchers with piles upon piles of spam. However, this cannot account for human ingenuity.

Any Lock Created By Man…

There is an old saying that any lock created by man can also be defeated by man. What this means is that even the most secure and sophisticated locking mechanisms will have some kind of a flaw in them which will allow a human being to find a way to defeat them, given enough time and patience. The reasoning is simple: ultimately, there will always be someone, somewhere who is just as clever as you are and who can figure the thing out.
I personally haven’t tested this theory and I do know that some of the top locks and safes in the world are virtually impervious to being picked  or defeated by thieves, however, they all say they are “virtually impervious” because there is always the possibility that another human being will figure out a way to defeat that which you created.

Computers Are the Same

I personally believe that computers are the same way – ultimately, computers are still programmed by people and this means that no matter how sophisticated Google is in creating new and better algorithms to try to beat back spam, people will continue to innovate and find new ways around the spam filters.

People Are Lazy

Plus, no matter how much effort Google’s engineers put into eliminating spam, ultimately, they can’t eliminate the one thing which makes spam inevitable: human laziness and greed. Most people will always seek the easiest way to make money or get something done and will always try to find ways to “beat the system.”
That’s because most people, by their very nature, are lazy. They don’t want to have to work. It’s not anything against anyone in particular. It’s simply part of human nature. And this means that no matter how sophisticated Google’s engineers get in finding way to eliminate spam, they’ll never do away with the human desire to find easy ways to accomplish something and ultimately get away with something.