Since AFM, there has only been one unlicensed pin that sold above about 1,300 units, and that was RFM. So we're at 21 years and counting since anything unlicensed was "flying off the shelves".
I hope the game does well. But a well executed unlicensed theme is a niche within the already tiny niche of people who will spend thousands to put a pinball machine in their house.