The Great War was a pretty big deal in this reality, lasting for ten years and collapsing the economic structure of Europe. That being said, there is no rational reason why Sweden would have to join the war. Once the diplomatic house of cards fell apart at the beginning of the war, things were pretty much set. It was unrestricted submarine warfare that brought the US into the conflict militarily, but the US had been part of the war economically since its inception. Sweden's economy wouldn't be relevant enough to draw the same sort of reactions, so they wouldn't have any reason to join. This world does have Ethiopia join on the side of the Central powers in exchange for military support, but Ethiopia at the very least has solid reasons, having been humiliated by the British and only narrowly escaping colonization by the Italians in the last century.

And the Russian Empire would have no reason to invade Sweden. They could hardly hold on to Finland as it was, and if they wanted to turn their aggressions on a neighbor Sweden just wouldn't have been their first choice. With the economy of Europe having fallen apart, Sweden would probably have suffered as well. I imagine any militarization they would have done would have happened in the wake of Russia's crisis in Finland.

The thing is, I imagine Finland's military exercises now would be limited to naval actions against piracy coming out of the Communes. I can't see the Swedes watching the news hearing about massacre after massacre in Russia and Finland and thinking "Gee, we really need to get in on that." They would really have no reason to be aggressive.