Looking at the evolution if the M system so far, it'd be cataclysmic, frankly I can't believe it.
In 5 years they've managed 2 half decent prime lenses still haven't produced the perfect M series body, which would be rangefinder in style, having incorrectly assumed that the only people interested in mirrorless weren't interested in 'proper' photography. They don't understand a camera needs a decent viewfinder, and that doesn't mean it has to look and feel like an SLR.
For me the great advantage of mirrorless is the smaller body, and APSC allows for matching fast small(ish) lenses. The Fuji system is perfect, but I don't want to own 2 lots of lenses.