Nailed it. There's really no specific war aim that the rebels would have sought to implement. Even the 'Twelve Articles' were controversial. So what the outcome of a victory would be depends almost completely on the circumstances of who wins it, and how it is defined.
Almost certainly, it would include the ends of formal serfdom and some form of control over local priests. Very, very likely a firmly (if idiosyncratically) Lutheran church reform. Beyond that, it's almost impossible to predict. The ideal society many of the rebels envisaged is unlikely to have emerged because it had too many forces against it. But the revolt could end up breaking the power of the minor nobility and patricians, and ultimately serve to produce a state based on territorial authority over nominally free and equal peasants and townsmen with some form of political representation. I don't think it would look much like Vasa Sweden, but it would be so cool...