Only a question of what will be left, and how it will be fought. I put my bets on Russia and China vs. America and the British Union.
Oh yes. Most definitely. It will be fought between the conservative fascist business people who use ignorance and zealotry to inspire hate, and the leftists who believe in social freedoms and worker rights. Likely will end in nuclear winter.
Yes. The world is a ticking time-bomb.
If a World War 3 happens in this century I'd laugh because really it wouldn't be a Total War with hundreds of men slaughtered like cattle and economies devoured by Black Holes. I'm more guessing the war would be like another Cold War where both sides point Nukes at each other so no, I don't think it would be a World War but maybe a second Cold War or a Nuclear War where the world becomes a complete wasteland like Fallout
There actually have been multiple world wars before World War I so saying World War III happening soon will be politically incorrect.