At this rate, it could turn into a major accident.
かねない looks like the negative of 兼ねる but actually means 'may well happen' or 'could easily do,' usually about an undesirable outcome, unlike 兼ねる's meaning of being unable to do something.
Negative potential form of かねる (to be unable to do), literally meaning 'cannot not do', which developed into 'could well do'.