T-Mobile hasn't provided much information publicly for G1 owners to upgrade to newer Android-based phones. Perhaps, there is no upgrade option until the two-year contract runs out. For US users, there still isn't a whole lot of selection. For that matter, there is only one option besides G1.
HTC Hero, a very compelling reason for anyone to get an Android phone, won't be coming to the T-Mobile but will be available this fall for Sprint. But this winter, there could be more Android devices coming our way.
So, as first generation adopters, will you be satisfy with to see your friends and others watching around with a spiffy new Google device? Personally, I think the G1 is a great device that only shows the potential of mobile computing, not the fruits. It's always like that with first or second generation technology. However, as I travel the Web, I'm beginning to see more meat being added to Android. I don't know if we'll see it with Android 2.0 or the next version after that but it's good to see Google putting a lot of resources into this.
I was a bit worried when they announced Chrome OS earlier this summer. For instance, we know that VOIP should be support in up coming Android upgrades.
Will I upgrade from the G1 if I can? Definitely. I think what I'll be interested in seeing is how Hero does with Sprint with Pre being their flagship device. Also, word is that Motorola is looking to get into the Android game as well.
It'll be a year or so when a lot of these devices come out. I'm a T-Mobile guy so I hope many of these devices will also come our way.