Yeah, God forbid that the price of bitcoin actually stabilizes so it can be used as a viable currency. Who would actually want that anyway. 
/sarcasm
Not me. It would mean that bitcoin has failed. We are at less than a tenth of one percent of adoption right now./sarcasm
The level of adoption needed to be considered "successful" is subjective. All you need is enough people using Bitcoin in order to be able to easily liquidate, you don't need the whole world. For instance, I doubt even 1 in 20 people in the US have gold. Maybe 1 in 10,000 people using Bitcoin, is enough adoption. It doesn't mean Bitcoin has failed if it will always be used by a niche group.