Exactly my concern. I was actually looking forward to the gaming prospects of the Android platform after seeing the S3 beat the iPhone 4S in graphical performance. This was their best shot at getting a device out there in large enough numbers that maybe some developers might keep this phone in mind when making a new app.
Unfortunately, if only certain S3's have the super fast GPU, I don't think any games will be developed specifically for just the International version.
With the iPhone there are only three currently selling versions. It is very easy for the developers to optimize for only those three, or sometimes they just choose to only support the iPhone 4 and 4S to make things easier. I have seen dramatic improvements in graphic quality from for 4 to the 4S. Note, I did not say "game performance", since the devs can still optimize for the iPhone 4, ensuring a smooth frame rate on both phones. Either way the game performs smoothly, with no frame rate drops, but with more advanced effects and higher resolution textures on the 4S.
This is similar to the Console vs PC debates of recent years. Even with lower specced hardware, when a new console is released it usually has much better graphics than the best PC games available. This is possible due to the heavy optimization, since the developers know the exact hardware the application will be run on.
Since the Samsung Galaxy is always the best selling Android phone, it was a good opportunity to create a standard high point that applications can aim for. Unfortunately, this did not happen.