Of course, it could always evolve into something more. Wouldn't it be ironic if in a few seasons Desperate Housewives became the most intelligent, most thought provoking show on the air.
The Sopranos was supposed to be for 4 years only and David Chase had the main plot line already written. But 2 things happened, the actress playing the pivotal character (Tony's Mom) died and the show was a runaway hit.
I would have liked to think that Tony and Carmella would cash-in to the Witness Protection Program in the end leaving the rest of his psychopath buddies dead or in prison.