Bitcoin is not failed as a currency. We just need to hope that bitcoin will rise again. It's just part of the life of the bitcoin. It goes down and goes up. It will be back and make the people use of the bitcoin as a currency. I'm just waiting for it and hoping that it will be soon.
I do not have a general prediction with you. My personal opinion is that Bitcoin has a huge potential for becoming a currency. I made this prediction based on the potential of Bitcoin and what it has done. Actually Bitcoin has been used in many transactions and it makes this process faster and safer.