MAD policy appears to be effectively over, or at least there is no longer any mention publicly, perhaps it is just assumed. While it can appear crazy, hence the name, it was a rather ingenious way to solve the problem, albeit we know now we have come dangerously close at times, at least we knew the risks and the lines that had to be crossed.
The next point and somewhat related is the change in nature of nuclear weapons. The variable ability of tactical nukes to change their explosive size, has resulted in a modern range of weapons that aren't as destructive as their elder brethren. It may seem like a good idea but the issue is it also opens the possibility of their more active use. A state may consider it acceptable. This could result in the reverting to an older policy of nuclear weapons. The MacArthur plans to use them in active combat, it becomes too easy to dial the Nuke down, target a military base and say "sure it's ok it's a legitimate military target".
That to me is the danger in the modern world. Attitudes, at least Western are still as a weapon of last resort but I can't predict the future and say that will always be the case or that other nations will share the same sentiment.