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One never knows for sure with Google. I think there is a top secret repository somewhere that contains the formula for Coca-Cola, KFC's blend of spices and details of Google's search algorithm. From what I've seen, much of the change will be noticeable when people are searching for specific information using more or less natural language, and answers generated utilizing semantic search technology will appear along with the "normal" search result links. What this means, I think, is that SEO will evolve to include semantic considerations. There are some open standards available that can provide some guidance on this front, such as schema.org, but I don't know how closely Google will follow those existing standards. Probably close enough that you can get a handle on the basics of how to semantically mark up your content.
One thing that does raise my eyebrows is the revelation that the search engine will penalize "over-optimized" sites. Hopefully that means the word list/link bank sites. Where is the line between over-optimized and perfectly optimized? Only Google knows.