there is always this possibility. you can meet it when thousands of people sell their bitcoin. or when investments are declining. but it is a small possibility. because mining costs can not be produced below 5k.
You do not need thousands of people selling bitcoin to have a major fall, big whales could make a difference too, Mt Gox certainly sold many coins in the past few months and they are the major reason for the crashes we are seeing every now and then, you cannot predict anything when it comes to bitcoin, i am not sure about the mining cost will be a major factor when it comes to bitcoin price.