flyboy,
first I want to suggest that maybe this question should be in the 'Modern' section.
second, to answer a question like that needs a knowledge of all the differents factors involved.
...some war in Europe starts...
I don't think you will see anything like that happen again unlessther are some very drastic changes. Most wars today are not fought in the way that WWII or WWI were fought. Its not about what part of the earth you are standing but a more cultural problem like Iraq, Somalia, Darfur, etc. Even Palestine and Israel goes deeper than who owns the Gaza.
And with the European Union, its unlikely to fins a major war against other nations who are members. Some squabbles and bickering but nothing on the scale of WWII.
...russia get in to it ....
The Red Bear is dead. They still have nukes and there may be a question as to how sincere they are in joining the global community but I don't think that the evil in the world is coming from Moskow anymore. At least not on a scale of a WWIII.
Most of your evil-doers nowadays who can even think of a WWIII are those countries that are still holding onto old style communism - like China or North Korea - or have a cultural, religious attitude towards the world - like Iran. I don't think nukes on the scale that we were brought up to be afraid in will happen but.....
Small strikes by limited nukes and/or crazy groups or terrorists who can get ahold of them, most certainly will happen.
Its a very complex issue, flyboy, and I'm sure some of my post may be incorrect but the upshot is, keep informed by reading the news and always keep an eye open for how that news will not always tell you everything.
Read the news and read between the lines.