Seriously.. Why does THE important thing for bitcoin seem to be how many merchants take the currency? I mean.. good luck going anywhere with a bar of gold and buying services.
No, it's like this: The best thing for bitcoin is adoption.
Adoption can come in many forms. vendors could decide to accept it (slowly over time). Some mega-corp (like visa, western union or some bank) decides to start using to move money internationally. It replaces paypal by becoming easier to use, more reliable and less of a headache.
Heck if all it got used for was domestic western union style transfers - we'd start seeing a massive upswing in transaction fees.