It is a telling sign that CBS News didn’t invest in the usual sky box for its anchor, Katie Couric, in Denver. It is equally telling that CNN consistently beat ABC and CBS in last week’s Nielsen ratings, and NBC as well by week’s end. But now that media are being transformed at a speed comparable to the ever-doubling power of microchips, cable’s ascendancy could also be as short-lived as, say, the reign of AOL. Andrew Rasiej, the founder of Personal Democracy Forum, which monitors the intersection of politics and technology, points out that when networks judge their success by who got the biggest share of the television audience, “they are still counting horses while the world has moved on to counting locomotives.” The Web, in its infinite iterations, is eroding all 20th-century media.