Well, the main issue of Sony is really the lenses. Both in number of choices available and in quality available.
And yes, Sony is a huge company. Thats why, among other things, they make sensors. Since they can afford the initial investment of creating own sensor factories in the first place. And they make them for everybody, by the way, not just for themselves and Nikon. However, that doesnt mean their cameras are as good as Nikon when it comes to sensors. Ironically Nikon somehow seems to have the better Knowhow to get the maximum out of Sony sensors. They also seem to get the better sensors, despite Sony making them. The new D810 sensor, for example, is probably again a Sony - but Sony doesnt offer it in any of their own cameras.
And the autofocus of a good DSLR, such as a Nikon D7100, is of course still superior to what mirrorless offers.
However, the A6000 indeed isnt a bad offer.