Good stuff!
Although the predictability seems to be increasing, it's not rising appreciably. Note in the first figure that the scatter of the data is actually decreasing... there are less wildly predictable and totally unpredictable shows. I'd submit that Phish 3.0 are more mature musicians, so perhaps they're finding a better formula that works for them. Maybe they're trying to let certain songs evolve to a greater degree before rotating them out?

It'd be interesting to compare these trends with a proxy for how 'enjoyable' the shows are. Does predictability correlate with awesomeness?