It can be estimated that at that time there will be the war between Google on the one hand and a team of Yahoo+Bing on the other trying to gain more shares of the search engines traffic world. Google being heard of constantly updating its ranking algorithm would also be the everyday news.
This has been today's Chinese whispering game. lol. SEO will stay around for quite some time not unless all search engines are blocked in all countries. Still, I highly doubt that it'll happen.