The great interest in the MiniMIG has several points:
1. Its small form factor opens new options for perhaps an Amiga compatible device in a joystick sized device.
2. As such devices are developed and produced in larger quantities, it may spark more interest from non-Amiga users that buy one to look backward and learn more about the Amiga history and the fanatic following that still exists after so many years beyond the Amigas supposed death. This may lead to a small increase in new Amiga enthusiasts.
3. More importantly, as others have stated, this project is just a beginning point for others to build on and branch off in as yet unknown directions. It is Open Source and could take off in the right hands. Don't laugh or discount this idea, nostalgia is very big right now and the buying power of middle age people everywhere is huge. Also the beginning point that Dennis has given us may lead to the REAL NG Amiga that most of us on these forums have been waiting for.
I am an optimist and don't think that the above is unrealistic.