It's been posted in dpreview Sigma forum since the DP1 came out 5 years ago. There are Sigma employed posters there and so I am sure Sigma exec's know it. Sigma dslr/dp series are their side business to their money making lens business. It make more sense to have an open mount esp with their latest high IQ lens designs. Faster lenses would be nice esp when the high ISO colors have problems with the sensor. Hopefully they will do that in the future...
Anybody think that Sigma will ever come out with a compact (dpm size) interchangeable lens system? That would be a lot of fun!