Perhaps they chose "8" for the same reason it's popular with ice hockey players - it's the "biggest" number visually, and obviously to indicate this plane is not just a continuation of their existing portfolio.
I'm surprised at how elaborate belief structures people are willing to support just to make the A380 (almost wrote A3xx!) look doomed. It's just a big plane. There are many routes in the world with sufficiently heavy traffic. Flying it is both cheaper and a bit comfier (in economy, a lot comfier in biz) than other planes. Airlines are obviously interested.
Some think BWB is Boeing's answer to A380. Unfortunately we aren't going to get rides in blended-wing a/c for a while yet. Both Boeing and Airbus have been looking at these designs for decades, yet there is no product on market. How would it be certified? How does it behave at high and low speed? How much more expensive is it to r&d and build? How fast does it go? There are some setbacks, for instance the A380 can be stretched and shrunk at relatively low expense, whereas a BWB family would be prohibitively expensive. Designing one model costs more than designing one conventional model. Subsequent conventional derivatives are cheap, but BWB derivatives are still very expensive.
Mayhap we'll see them when aircraft switch to hydrogen fuel.