i dont think that the difficulty will ever be lower than it is at any point in time. meaning it only gets harder because it is growing and more poeple are adopting and to spread the wealth more the more users needed mining and supporting the network and the network gets bigger
There are a lot of marginal miners now with older miners that make just a bit more than the cost of the electricity needed to run them. If the price of Bitcoin drops significantly, they'll stop mining. However, even though there are a lot of them in number, they probably don't represent a huge fraction of the mining power out there. Still, it wouldn't surprise me if difficulty temporarily dropped a bit if the price of Bitcoin, say, dropped by 30%.