"Double, double, toil and trouble"... Shakespeare's words (Macbeth, Act 4, Scene 1) often cover circumstances beyond his wildest dreams. Toil and trouble accompany major computing transitions, even when people plan ahead. To calibrate "tomorrow's legacy today," we should study "tomorrow's legacy yesterday." Much of tomorrow's software will still be driven by decades-old decisions. Past decisions have unanticipated side effects that last decades and can be difficult to undo.
Today general-purpose processors from Intel and AMD dominate the landscape, but advances in processor designs such as the cell processor architecture overseen by IBM chief scientist Peter Hofstee promise to bring the costs of specialized system on a chip platforms in line with cost associated with general purpose computing platforms, and that just may change the art of system design forever.