Could the use of a white noise machine create dependency in the long run?

Possible: You don't give much detail, but I assume you're using it to help with your sleep. If it works good for you! White noise machines are very portable white noise can even be made by your phone overnight. Believe me it won't be a dependency like cigarettes or heroin, but whatever patterns of behavior are associated with sleep sometimes becomet he prerequisite for sleep. Sleep on!