>perhaps have been inclined to stay neutral at the outset of WWI then join forces with the Central Powers once it became clear that neither France nor Russia could survive a prolonged war against Germany?
Also, just after typing out the previous post I remembered something that had in my head a few hours ago. I imagine during the great Germany-AH versus France-Russia showdown Britain would first support the former simply by trading with them while refusing to entertain the other side. America I think would just try to be a good capitalist and sell anything and everything to the highest bidder. Depending on the situation, I can see Britain blockading France (it's not that hard if they are on the other side of that channel, and they control Gibraltar), and that could trigger a naval war between them and the US of A. Of course Japan would immediately join the fun on the British side, and then we'd see some fun things happening.
Even more, I imagine that if they can win the initial naval battles, then Japan would go the extra mile and declare war on Russia and France to grab French Indochina and as much of Siberia as possible. And it would happen well before the Second Sino-Japanese War, therefore they could throw their full weight into these conflicts, especially to the Siberian conquest. And it's only natural that they'd try to get the Philippines, but that's not important here. Still, just imagine if Japan actually managed to get the parts of Siberia that had some actual resources, and then started a war against China.
And one more thought: Canada was still a British dominion in those times, therefore they'd be obliged to declare war on the USA. Now imagine all that clusterfuck, especially if the Japs also decide to land in Alaska.