Bitcoin has already become a global currency, It did this when it was trading on the Stock markets, yes as a stock, but also as a currency if you look at the stock exchange you have all currencies traded, and then the commodities market is also Bitcoin. so it is in all levels of trade, and currency exchanges, this is what keeps it strong, and will make it stronger for days to come.
I travel alot around the US and I have found that many places take bitcoin. Restaurants, Hotels, I stopped at a truckstop a small private one and it took bitcoin. When you start seeing bitcoin in small private businesses you know that major chains are going to take it up fast to keep up with the private businesses. Next time i will write down the names of the places that accept bitcoin so that way I can post it.