If you build it that only one game can be hold and the rest is space for game data than maybe its a developer tool.
There are only about 10 developers at the moment, and i think you found not more than two who will/can use this.
Iam one of the developers who dont want to use it.
The problem is if gamers require this to play a game thats not fair to the gamers who dont want to buy it or dont get it.
And about the space. At the moment there is no game in development that uses more than 512KB why should it make sense to have more than 1GB.
I have a own system for sharing saved games and levels from one lynx to another that i will use in future games.
If you build it to hold masses of games on one SD-Card, its a tool for piracy.
Regards
Matthias