One of the best things about the Contax G system-- which is what I still mostly use (21, 45, 90)-- is that in addition to having great lenses, it feels "right" in the hand. A while ago someone started an off-topic thread about What Kind of Pen do you Write with?-- There is a correlation. Many people in the RF forum truly dislike the way DSLRs feel in hand. They feel wrong, just plain wrong, as if they had been designed by beings more interested in medical study of the human organism than by craftsmen with thumbs and four fingers. The Epson RD-1 does, to my hands, feel very. very right. When Leica built the M5, actually a terrific camera, a lot of people didn';t like the way it felt in hand. Leica should follow their hands.
Yes, I agree-- in addition to the feel of the camera, it should have the best VF of anyone, bar none, since the price is likely to be the highest of anyone else's bar none, after buying new lenses (since my G2 lenses are dead-enders).
Yes-- again, harkening to the medical labs inspiration behind dslrs-- minimal menu litter. Should be non-intrusive, easily hidden.
Finally, to make this the last camera I ever have to have, any new lenses should be developed to cover the inevitable loss of the widest angles due to the less than full-size sensor. 24, 21 for starters would be attractive to me-- again, hewing to the same feel and quality as existing M lenses.
I'd rather wait, say, two more years, using my little Ricoh GR and film as a stop-gap than have the digital M rushed to market (even rushed for Leica!). When I commit my money to Leica, and it seems likely that is what I will do since I believe only Leica can really pull off a classic digital camera, I really don't want to have to upgrade for a minimum of seven years. I mean, maybe there'll be a second DM in that time, but I should feel the camera I have bought is still so good I have no need to have to junk it for a newer model. The basics of that near-perfect DRF have been covered well by many other here. So: get everything right, near-perfect and then release the camera. If Leica can do that, they will probably own the RF market, as they did when they released the M3 in 1954. I hope they can.