So are they right? At this point, probably. This tablet has been quite thoroughly leaked in the past couple months. Even if you ignore all the rumors, the (deliberately) leaked benchmark test and the (deliberately) leaked photos both suggest that the launch is imminent.
I would expect, though, that most of the other manufacturers would prefer that it not appear next week. Past leaks suggest the Nexus 7 is probably going to be running the latest version of Android 4.1 on a 1.3GHz Tegra 3 CPU. Screen resolution will be 768x1280, and we know from the photos earlier this week that the Nexus 7 will likely have a 1.3MP camera.
If this thing really hits the market at the predicted price of $199 it's going to play merry hell on everyone else. It 'll have better specs than anything else at that price point, so at a minimum we're going to see price cut from just about everyone. Hell, I think even the sub-$100 budget tablets are going to feel the pinch. The Nexus 7 will likely cause a glut of returns, and when those tablets show up as refurbs the bottom of the market will drop.
And the more focused devices like the Nook Tablet and the Kindle Fire will likely both drop below $200, just to stay competitive. And there goes B&N's market share and what little profit margin they had left.