Nikon and Canon are boring and lagging behind in the R&D.
of course because if they make a killer mirrorless camera it would cannibalize the sales of their DSLR line.
all they can do is sell and overpriced and underpowered mirrorless camera and that's exactly what they're doing now and i'm sure they know very well it won't go far but it's their choice and things can change overnight if and when the demand for pro mirrorless will start to grow.
i think we'll have to wait 2-3 more yrs before there's serious demand for mirrorless among pros.
and then it will cost as much as a pro DSLR (2-3000$) so what's the point ? you think they'll sell for 500$ ? no way.
i remember when the D3x came out .. 8000$ !! just because the sensor was 24MP, hahaha.