Canon responded by buying more Sony share;
Then Sony stab Nikon on its back to bring out a7 & a7R
Then there are new sensors coming that surpass the Sony sensor. But I imagine that Nikon will keep an eye open for new sensor technology, just like Canon. Camera bodies and lenses is what Nikon and Canon will be concentrating on, although I have no idea what Canon will do relating to producing its own sensors. That technology is rapidly changing out there.
In my view Sony will do fine for awhile, but Nikon and Canon have most of the market on brand loyalty.