I signed up here because of this project - looks really promising especially since it has already started with the nt mini.
I really like the idea of a modular system running off SD cards with options for analogue AV, cartridge adapters if you want them, standardised connector for pad adapters - sounds amazing!
A few questions if I may;
Is it likely that the Z3K will be able to support SNES, MD & PCE?
With regards to MD & PCE are CD hardware cores feasible?
Is it possible to implement tools for the gameboy cores for backing up saves/data from the carts, I think it was mentioned there are similar tools in the NES core for dumping the cart?
Are you planning to build in bluetooth support for pads?