All we can do is guess based on what we know. And one thing we know is that it's ludicrous to develop something like that and then just abandon it. No one would do that unless absolutely forced to do so. And my guess is that initially there must have been (putting it very generally) some kind of organizational issue. And then the economy woes creeped up and eventually beat down the door. So one thing after another perhaps.

I think something must come eventually. That's just my belief based on what we know (and assuming that someone at Horizon Hobby has a brain, which I'm sure is true).