Arg. Tom Edsall is -- perhaps by accident -- confusing demographics and politics here.
Transforming politics is one thing; transforming demographics is something else entirely. Senator Obama, by all measures, has already transformed the way a presidential campaign is run (small donors, flawless branding, no PAC or lobbyist money, the Philadelphia Address, etc). He's already transformed the racial and ethnic qualifications for president and broken through insurmountable barriers (a black candidate defeated a white candidate in Nebraska, for instance). This is an entirely new, entirely "changed" political campaign from the top down.
In other words, he's already a transformative, historical political figure. Just because his demographics might be similar to Senator Kerry's -- and I can't imagine that they are -- doesn't mean he hasn't significantly changed the way the game is played.