I know hindsight is 20/20 and we have the benefit of looking back, but it seems like a clash of at least two of the great powers stacked with new industrial revolution weaponry, mobility, and lethality was inevitable, much less plausible, and yet, it seems it went largely unexpected by the experts. Why?
Can you justify where you heard this claim that war was unexpected by "the experts"? I'm not trying to be snarky; this legitimately needs to be explored here. Who are "the experts" you're speaking about? Why do you believe that European powers were not aware of the hardening political boundaries between the German-Austro-Hungarian and Franco-British-Russian trios or that they weren't preparing for the realities of 20th century warfare?
Again, I'm not trying to be snarky here. It's just when someone comes in asking a question that is, to be frank, based on misconceptions it's useful to ask where these ideas are coming from because there's usually some more misconceptions that aren't immediately noticeable underneath it all :)