Jeri Ellsworth managed to showhorn a C64 into a joystick for a lot less than the projected price of this item and the DTV can easily be hacked to support an SD card and a keyboard. Something like the DTV would have been a better basis for a C64 replacement board in a similar way that the Minimig was for the A500.
This replacement of Jens' is an exercise in re-inventing the wheel in my view.
I think DTV is an FPGA, the C64 Reloaded is the real deal, I guess.