Ricoh offers an interesting design alternative with its GXR system in which each lens has its own sensor permanently attached to it and designed to match the expected usage of that lens.
this may suit a few people wanting some mirrorless capabilities and the option of a point and shoot compact 10x zoom in the one system but its main downside is that as sensor technology becomes out of date, you not only have to change the sensor but the lens system as well, which is likely to mean a more expensive longer term cost.
the body has a built-in pop-up flash, hotshoe and capability of adding an external viewfinder onto the hotshoe.
the terminology on lens focal lengths belows are not actual but 35mm full frame equivalents.
I really can't see this system going anywhere, particularly with the lack of progress in updating sensors or lens options