A 30 Years War with modern weapons won’t ever happen. That’s the ‘beauty’ of modern weaponry.
Highly effective weaponry being on either side of the conflict does not cancel each other out. It just means that the war will be over quicker, because of faster means of transportation, more deadly weapons and shorter average lifespans of soldiers than either side could even dreamed of 1618 - 1648.
Also, the conduct of war has changed. Part of the reason why the 30-years war lasted 30 years was because the conduct of war during that time was based on outmaneuvering and sieges, with a priority on avoiding actual battles and rather starving enemy armies by cutting their supply lines.
As for “A World Order” coming to its end, I don’t think that is the fact. We’re running towards a war that will be fought to affirm our current World order, and I am positive that our modern political Culture will end soon and be replaced by a new culture, but the economical and political dominance of the West won’t end so quickly…
World politics will be less about “Making/keeping everyone semi-happy through compromises” and more about “We need this, we’ll take it, if necessary by force”. Sadly this will probably lead to the UN becoming less dominant whereas the NATO becomes more so.
Even us Europeans will then realize that our post-colonial “Be nice to everybody and stay extremely politically correct” attitude might not be the best for the times…