It's already up to 32GB, I don't see a jump to 64GB with the current generation hardware since it's going to be a while (at least another year) until 256Gb MLC NAND flash chips hit the market. Apple would need to find a way to pack 4 chips inside of the Touch to hit 64GB any sooner.
You can also basically rule out price drops, and a camera on a MP3 player is unlikely.
The earliest upgrade will be after introduces a next generation iPhone. If they upgrade the processor, RAM, or GPU, then that'll likely trickle down in to the Touch.