I think it's highly improbable. The software at Yahoo Answers does not do a good job of empowering the community to "weed the garden". The result is very low quality questions and very low quality answers. See How Is Babby Formed? | Know Your Meme for some humor about this.
Here we have a diligent community and software that allows us to filter out low quality content. We also have a company that appears to understand the importance of a quality community. There are lots of incorrect ways to think about a site like this: one of them is to notice that traffic grows with the number of pages due to natural SEO and therefore structure the software to encourage the creation of lots of pages and the deletion of none. That's a false economy as you ruin your longterm value and image if you don't strive for quality.
(1,000,000 useless pages will generate a certain amount of traffic - 100,000 great pages will generate less traffic today, but will attract and retain a quality audience of thinkers who can build more. This takes time. I'd rather see Quora growing 50% a year with quality than 500% in one year and then dying because it's nothing but junk.)