Tilt Brush (the google) equivalent is amazing, and I think we're going to see more tools like this evolve over time, but the use cases for visualization will be more obvious up front than sketching. Car designers and other professions have been using VR/CAVE/MR systems for a while now to visualize large scale objects which are too difficult to see on a piece of paper. Likewise, architectural visualization will be completely replaced by VR within the next several years IMO. Being able to understand a space in 3D far outweighs the low barrier to entry.
The ability to sketch in 3D is really cool, but obviously as a profession we've spent decades evolving the "Art" which is ID sketching. ID sketching is about communication, and working in 3D allows you do do some really interesting things in terms of helping you to understand space, but unless someone straps on your headset and looks at it, the 2D representation you see in these videos is never quite enough.
As far as outputting to CAD, everything you see rendered is polygon geometry, probably based on the 3D Bezier curves you draw with the wands. So it's automatically going to be water tight when it comes to sending to a 3D printer.
If you haven't had a chance to play with Tiltbrush, try to scour your networks for someone who has a Vive. I spent about 30 minutes Giggling the first time I drew a shitty VW beetle in 3D.