How would subversion fix this problem exactly? It would still be a centralized forge that Microsoft could still control/ruin. In fact, more centralized than Git, which itself was designed to be decentralized (though admittedly most people don't use it that way).

Microsoft didn't purchase "Git", they purchased Github, the largest forge for Git. Git will continue to exist no matter what Microsoft does.

Also, I have absolutely no desire to ever, ever go back to SVN. When I was a junior engineer in my first software job, every Friday I would have to do The Merge, which would usually take most of the day because it would be spent solving all the merge conflicts. When I discovered the git-svn thing, it was like manna from heaven since it made a 4+ hour job take around ~45 minutes.