All black would be fun for the hardcore types.
Astro and Mono versions would be a hard sell.
Why would you want to change the shutter button feel? It is pretty close to perfection imo.
You have choices in the paint colour already, Black / Silver - Gun Metal will be a run out edition in a few years.
The MF with brighter prism? now that could stand alone and be a seller, especially if you have a collection of the back catalogue (which a lot of us do), the back catalog also work better in most cases with a crop sensor, the K-1 series highlights their deficiencies all too readily.
PS I can already hear the screams of anguish as the FF brigade start frothing at the bit - 'but the back catalog is designed to be used with a FF sensor, sacrilege and heathenism to suggest anything else!".