A lot of people still don't know what the G1 is. Hell, a bunch of people don't even know that Google released a mobile OS. And if I'm not mistaken, the G1 was poised as an iPhone killer as well, same as the Blackberry storm, the Samsung Instinct, and all those touchscreen LG phones. The iPhone is still going strong.
The Pre looks like an okay phone with a solid OS, but I'll put money down that it'll end up being in the list with the other "iPhone-Killers" when the next hyped iPhone killer is announced. And I bet you the iPhone will stay distinct from that group.
All this talk about iPhone death and defeat reminds me a lot of the MP3 player war that was, and is still, going on. A bunch of companies released a bunch of "iPod-killers" with wonderful reviews and board members saying that the iPod is doomed. But the iPod is still here and going strong, while the iPod-killers have faded into history. The only MP3 player I keep hearing about as much as the iPod is the Zune. And that has nothing to do with Zune being a good mp3 player; it has more to do with the infamous relationship between Microsoft and Apple.
The iPhone is going to be fine, and there will be no running for anyone's money.
BTW, the Pre has had too many mixed reviews. I hear the battery is great, then I hear the battery is not impressive at all. I hear the keyboard is crap, then I hear the keyboard is fine. We'll see how well the Pre does once it gets out to more regular consumers.