Jamais Cascio offers a fun and useful concept, "legacy futures." These are inherited visions of the future, as the term suggests, drawn from whichever source, and which shape our futurism.
Legacy futures are rarely still useful, but have so thoroughly colonized our minds that even new scenarios and futures models may end up making explicit or implicit references to them.
A couple of thoughts. First, as the comment stream suggests, digging into history helps avoid some of the legacies.
Second, paying attention to the imbrication of new stuff upon the still living old. What one book refers to as The Shock of the Old. The new doesn't always drive out all of the old - in fact, rarely does.