Here's the important part: Daydream is not a standalone VR headset, and is not competing with Oculus Rift, HTC Vive, or Sony's PlayStation VR. Instead, it's an attachment for your Pixel smartphone (also announced today), which makes it basically the same as Samsung's Gear VR, except for Google's new line of phones.
Gear VR sold pretty well, but the fact that Samsung has recently announced that they're keeping their "standalone" VR headset (in the sense of including the display elements in the headset; Gear VR and Daydream both need your smartphone to provide the screens) offering on the sidelines until they see how the VR market shapes up speaks volumes -- that even a company with a decently-selling mobile VR products is staying out of the more expensive home VR market says quite clearly that the success of standalone VR headsets is no sure thing.
Whether Google will sell enough Pixel phones in a mature smartphone market to be able to sell enough Daydream VR accessories to actually compete with Gear VR's market share is, of course, anyone's guess. It would seem that Pixel is aimed more at the iPhone than the Galaxy Note, but sales of all smartphones have plateaued recently, mainly because everybody already has a good-enough phone, and thus no pressing need to upgrade.
Added to which, Google's previous forays into consumer electronics, including both the now-defunct Nexus phone and the now-defunct Google Glass, don't exactly inspire confidence in Google's ability to compete head-to-head with Apple as a manufacturer of consumer electronics.
The Pixel does look like a good phone, but at prices ranging from US$650 to US$870, MSRP, data plan not included, it's tough to imagine Pixel taking any significant share of the smartphone market away from long-time iPhone customers, or from other Android phone lines. I could be wrong, of course, but I can't help but feeling like this move comes at least a year too late.
I feel confident making one prediction, though: Google's not going to sell enough Pixel + Daydream bundles to make VR into any more of a thing than it is now.