I'm a Pathfinder fan. I have all of the hard cover books, several adventure paths, etc. But THIS is the game that I want. A more focused, easy-to-reference, faster and leaner version of PF. The way monsters are presented is far more appealing to me than the existing Bestiaries. The truncated spell descriptions. The more focused choices. Better all around for me.
I really hope Paizo reconsiders their position not to develop this further. I can't speak for others, but an Intermediate Box detailing levels 6-10 and adding four more classes would be an instant sale for me. Moreover, it wouldn't stop me from purchasing the "advanced" PF books either. The fact that this set is selling well to established PF players would indicate to me that there is a market for more. I'm not advocating a massive line, but a few more products would be sweet.
If not, I hope a 3rd party takes it up.