About Japanese history again but a (relatively) simpler question, what if Ishida Mitsunari's Western Army (technically Mori Terumoto's, but Mitsunari was de facto leader) won the battle of Sekigahara?
I think Toyotomi Hideyori, unlike his father, could qualify as shogun, since I believe you had to be able to trace yourself back to the Minamoto, which Oda Nobunaga could and Hideyori was his grand-nephew. Don't know if Mitsunari could, I know Mori Terumoto might be able to qualify since he was descended from a Minamoto retainer.
If Mitsunari became regent, well I've heard people say his governing style and mindset was closer to that of a more modern ruler than Ieyasu, but I'm not quite sure what's meant by this.
I bet sakoku would probably happen anyway, since the Toyotomi were no more comfortable with Europe than the Tokugawa. Ishida victory at Sekigahara could spill over all the way to the Boshin War, since it'd flip the losing and thus vengeful clans, unless maybe Ishida was fairer on his enemies than Ieyasu, but no source I've come across suggests this.