They are all relatively successful (aside from the Dees). If we're talking Premierships as the sole yardstick for success, then there are actually only three successful Victorian clubs in the past thirteen seasons.
I wasn't using that yardstick though. I was using the entire history of three of the four, and Melbourne for the last fifty years. I was also not only referring to on-field lack of success, but to financial problems and a very limited supporter base (North, even at the height of their on-field success, seem to have troubles with both of those).
As I noted above, ideally I'd love a viable, competitive tournament (both on- and off-field) that features all existing clubs plus a few more, both to represent AFL heartlands without a team or with insufficient teams - e.g. Tassie the former, WA the latter - and to penetrate new markets, like Northern Queensland and New Zealand. 24 teams in particular would be very welcome as we could finally return to a non-compromised fixture. I can't think of much better. But if there is little ability to expand beyond the existing 18 thanks to talent dilution (this is the important factor here; I'm not saying we need mergers just for the sake of it, or out of disdain for the teams involved), there are three options:
1. Merge the weakest Melbourne teams so that they are more competitive, and so that one or two new teams can be established in Tassie, etc.
2. Relocate and rebrand an existing weak Melbourne team, and hope it is accepted by its new home rather than viewed as a cast-off.
3. Keep the competition unchanged, leave traditional AFL areas unrepresented in an allegedly national competition, fail to spread the game to new markets, and risk other national competitions taking the AFL's market share in its absence.
To me, #1 is vastly preferable, especially given the AFL's current programme of aggressive expansion.
(Of course, it's a shame nobody in the 1980s had the good sense to create a proper national competition above the state leagues, using state teams as feeders to ensure support, rather than letting the VFL grow into the AFL...)