If you do SEO correctly and follow search engine guidelines you’re SEO efforts will last. There are common themes that search engine’s have focused on for the past 5+ years that really haven’t changed. At Eyeflow the backbone of our SEO process hasn’t changed all that much it’s just small adjustments here and there when we see search engine’s making a shift. For example we saw that social media was taking off a good 5 years ago and we started including social media features in our SEO campaigns way back then. There where still SEO benefits even though at the time there was no official announcement from search engines. As of December 2010 major search engine’s announced they are using social media signals and since then have really increased their efforts. I guess what I’m trying to say is a good SEO company evolves their strategies before the search engine’s evolve their algorithms. Check out Google’s Guidelines: http://support.google.com/webmasters/bin/answer.py?hl=en&answer=35291
You may call them changes, but I would classify them as improvements and updates to improve relevancy of search results for search engine users. Remember... THE INTERNET IS GROWING EVERYDAY! The more websites that are online, the more potential results Google and other search engine have to offer to search engine users. Google wants to provide search engine users with results that are what the person searching expects to find. Google is not making updates to make search engine optimization harder for SEO Experts, they are making changes and updates that do a better job of sorting through all of the potential results, to give search engine users what they want. Google want to encourage NATURAL WEB DEVELOPMENT, not a bunch of people using software to post hundreds of links and automatic generated text.