IMHO, Nikon missed the boat completely for serious shooters with their mirrorless announcements. Based on all the comments that have been flooding the interwebs I believe this is an excellent, gentle wake up call for Leica. Here's what I believe Leica should develop for their mirrorless camera:
1. M mount (obvious)
2. APS-C sensor, no smaller (1.5X multiplier max)
3. CMOS with great ISO 3200 performance
4. High quality EVF (1M pixel or more)
5. 960K pixel LCD
6. Keep the body as small as possible
Feel free to add your "must-haves".