It can never be 0. As in Calculus it can only be .000000000001. The limit, remember that?
As VXX goes lower than 10, Barclays reserves the right to reverse split the stock at say 1-4. So it become $40 again and its public offering becomes $1600 on the long term chart.
Barclays states that anything under $25 can be reverse split by them. We are already in that territory.
But yes the answer to your question if you read the prospectus is that this product has a 100% guarantee to go to 0. The papers tell you "you will lose all your money."
This is a derivative of a derivative!! I mean holy @#ck, I see more volatility in the volatility index so I am writing to Barclays to see if we can create an index whereby we can trade the volatility of the volatility! Wonderful but it also will go to 0 over time ;)