I had never heard of the GallarHorne until I heard it mentioned on the Howard Stern show of all places. They found videos of people losing their sh*t when they found it and thought it was funny (it was)
As far as the PC version coming too late, it's easy to see why they put it to the backburner since they were developing for 4 consoles already and Bungie hadn't made a PC game in like a decade, so it was better to just focus on consoles. Don't forget that Bungie and Activision have a 10 year plan for Destiny, so even if it were to come out in 2017 they could easily release the game with all the DLC up to that point included.
I'm a little torn on Destiny. I've thought about giving it a third try, but I don't really throw like throwing down $60 for something I'm not sure of. I know they released that "free" edition a while back, but the beginning parts of Destiny that I tried out in the Alpha and Beta were just so damn boring. Again, it's one of those games that's better with friends/teammates much like Borderlands (along with MANY other things with Borderlands), but sadly I don't have those, and I think my 5 year old may be a little too young for the game.