I think it will take some time, until the complete case is finished, the bare cases are still not in production. Then the keycaps are needed, and then the complete new keyboard. It can easily take another year or so, until everything is ready.
I hope somebody will build some kind of adapters for the MiST buttons until then. Ideally, the 3 Buttons should be placed, were the floppy drive is expected.
Until then, I will use my PC keyboard. Indeed, the MiST+MinimigAGA is nearly perfect already, some small graphic gliches have to be fixed, that keep me off playing some games.
The only thing that is really missing is the color "Commodore Beige"