The aging of info is a concern in any biz, online or off. One is best off structuring a business model with several profit centers that pay off short, medium and long term. Clearly, blackhat stuff should be considered the short term funnel, as it is the method facing the most active opposition. Then again, some past 'white hat' seo methods got designated as spammy with a single Google algo change.

Look over one's collection of ebooks and articles, and make the call as to which methods are the surest, long term bet to be a lasting foundation for a monetizing empire. Pure white hat will likely be the long term plan, blackhat for the short run cash, and regular SEO that's in the 'iffy' category should be either avoided, or given some black hat modifications to work in the medium term.