I highly doubt it will be. And this is coming from an owner of a GTX 1080 and HTC Vive. There are some really awesome games and experiences, but there is nothing that I really want to keep going back to. No Rocket League or Minecraft (Well, there is vivecraft, but minecraft in VR just isn't that much more appealing to me than the vanilla game.) PSVR might get some stuff but for now it seems like most large companies are just putting their toes in the water by giving out small tech demos.

VR needs a couple of things, and they aren't going to happen in less than a year. First and most importantly, cheaper and better hardware. Daydream is nice, but at most it is good for 360 video and some cheap games. Get some head tracking in there somehow and then it becomes interesting. Also, it needs something like the oculus touch controllers or vive controllers so you can actually use your hands for things.

Secondly, an actual killer app. Some kind of game that only works in VR. Something that you want to keep coming back to.

Lastly - simplicity. Daydream is simple but too limited. The vive has all the features but setting up lighthouses is a pain unless you can permanently mount them. Also being tethered to your computer sucks (A solution for that is on the way, but it will only add to the cost.) Headsets are still bulky and uncomfortable to wear for long periods.

My point I guess is that Apple's typical timing with things would put them entering the market in 2018 at the earliest. This is like the early Windows Phone/PalmOS days before the iPhone (But I doubt Apple will be the one releasing the "iPhone" of VR.)