Pfft, never going to happen.
The west isn't interested in a war. Putin likes the bravado and it helps him win elections. And NATO is second to no one, and completely dwarfs Russia, in military capability.
I'm not losing any sleep over it.
Besides, people are becoming more connected and, although it might not seem it at times, more tolerant and accepting of others. With that comes less desire to butcher each other.
100 years ago, well let's pick another number... 104 years ago people were excited to go to war with each other - to keep those huns in check, or to have another trafalga, etc etc etc. Only the most isolated nations have any real risk of going toe to toe with each other - and that's why I think the real risk to peace is not Russia etc, but a possible insular China and the rise of protectionism and extreme nationalism.
People have to keep talking... we keep that up, and they'll be no WW3.