*Facepalms*
Has everyone who posted forgotten that Ishida Mitsunari supported Toyotomi Hideyori. Now, assuming that Ishida won, we'll be seeing a massive purge of all the anti-Toyotomi/Mistunari leaders, after which I suspect that the same policies that Tokugawa implemented will be similar done. The only main difference would most likely be the conflicts with the Christians. Given how rigid he was, he would either do a stampdown far worse than Tokugawa, or perhaps just ask for loyalty.
And here's the most important part: Japan would most likely never have been able to get the same kind of peace "treaty" that it did with Joseon under Tokugawa. The main reason Joseon decided on peace was how Tokugawa was willing to give apologies, and also the fact that Tokugawa himself never was involved in invading. Without this good relationship with Joseon, it'll be likely that Joseon will continue to be on a military standing, possibly making it open to European technology.
So, INSTEAD of the same old Japan-wank that this forum seems to be addicted to, we'll be more likely seeing a similar rate of development between Japan and Korea, with Japan most likely focusing on trading with the south to overcome its blocked trades with the continent.