Earlier quoted context omitted.
I don't know the answer, but I do remember people saying that Google was making a huge mistake buying the unmonetizable YouTube.
YouTube is long form video though. Plenty of content to advertise on. Where are you going to cram ads in to vine without it being annoying enough for adblockers to nuke them?
Now I'm not saying that Vine is the next YouTube or even that it is monetizable, just that "we haven't figured it out yet" is not a convincing argument, and surely its userbase would be appealing to some buyer.