Bitcoin is a digital currency and you can use it in business of whatever size you want but talking about the future potnetiality about bitcoin yes it is really a big thing and even usefull to common level people. Decentralized system is what people will love in future.
I think the bitcoin will be used by general public in the next few decades. It will be reserve currency like the US dollar.
That depends on the mass adoption and also there are no big bugs that will affect the fundamentals of bitcoin.