It depresses me how little watched the Sopranos is in the UK, no drama of its generation even comes close to it.
I guess it's maybe something to do with the fact that the nature of the Storytelling doesn't 'grab' and 'suck you in' like more superficial melodrama of the Lost or 24 kind, that you really need to see about a series' worth of material just to start to understand how masterfully made it is (i.e. more like great literature).
From what I remember, Chase originally said there would be 3 series, then 5, and now he's said the extended 6th is "definitely" the last (?). Everytime the extension came I'd always be pessimistic about the quality dipping as always happens when TV Shows which are both great & succesful just carry on and on as their creators can't handle living without their Masterpiece, which inevitably ends up doing great damage to the Show (Simpsons???), but so far the Sopranos has completely contradicted this rule... if anything every series has surpassed the last.
As I say, I'd hate for it to outstay its welcome, but owing to the particular character and pace of the way it has developed over these years, i.e. you can have very many episodes without anything "significant" happening, I can imagine it remaining Vital even for a ten-season run (I've probably jinxed it now!).
.... Just my 2 cents.
PS. av2 - has any of the sixth season even been shown in America? or are you involved in some kind of seriously high-level piracy?