How likely do you think World War 3 is?

I've been extremely into this topic lately and as much as I'd like to see a mushroom or two I just don't see it realistically happening. The way I see it, is that all countries are scared to make a move, because so many civilians are at stake but that also makes me think, Putin could be the one to wipe-out North Korea, surely he wouldn't care too much about NK civilians and Russia could possibly wipe them out before they could even flinch.

But that also takes me to the idea, if WWIII does break out, who would win? North Korea for sure would disappear but would USA fall as their economy crumbles due to investors and stocks dropping as death tolls soar and industry are blown away, with widespread of radiation. If this happened as unrealistic as this may sound to some, whats stopping Russia from pulling a global domination? They could easily piggy back North Koreas fight and use it to their advantage. Especially if they teamed up with China.

What're your thoughts? Am I completely off or do my strange ideas sound possible?