Post by Dan J.S. Sopranos is going one more season after this new one... FYI
According to Movie Central in Western Canada: http://www.moviecentral.ca/content3/sopranos1-5/ Season 7 will consist of 8 episodes, to be aired starting in January 2007, (season 6 having 12 episodes).
Since the imperial period went arguably from the 90s BC (Sulla and Ceaser were tyrants, not emperors) to well into the 400s, this series could go on along a LONG, LONG time. A sequel might be the reign of Augustus.