It's good for Nikon, IMO. Canon and Sony both have cine equipment. This will level the field. While I moved to Sony, I don't want to see dominance, but competition.
This will level the field? If you think Canon's cine options are equal to Red maybe it levels it. However, I think this tilts the field away from Canon to Nikon's favor while leaning more toward Sony as well than Canon. Maybe Canon can tilt it back in their favor if they were to buy Alexa.
However, from what I see, Canon is filling a very specific niche and they're good at it. RED is the same.
So, it will not level the big three "capability" wise, but Nikon will have a hand (and feet) in cine market, which will provide them great feedback, development avenues and some cash hopefully.
So, they'll be able to compete in one way or another.