My kneejerk reaction is this will probably waste a lot of their money without much traction. But I'm also happy about Facebook wasting a bunch of their money...
What about facebook getting into legal trouble here? There is tons of prior art and companies with the trademark. Either facebook buys them all, or find another name
All depends if they can deliver on AR before anyone else.
Gotta remember outside of Oculus, their entire product portfolio exists on top of the platforms of their competitors. This is their play to own the entire thing from the foundation up and the resources they'll be willing to use to accomplish that will be huge and really their only competition is Apple because Google gave up.