The lull after the spike could just as likely show a drop off in bot accounts active during the US election. But that's immaterial because growth is not the same as success.

As long as it's got an active returning user base that gets value from the product and is able to curate their own experience, it's able to sustain itself based on the money it has/gains, people are building new tools to make it more engaging, and it's not being taken over by undesirable actors so that active user base starts to look at another solution, and sites increasingly see Bluesky as a driver of traffic to their websites, it think that would qualify it as a objective success.

If you have a different metric, please feel free to share it.