Some nice ideas there.
I’m not a fan of minimizing the user info in the topic view though. The personal touch of clearly seeing who you are interacting with is getting more important these days, not less. If anything, this view should only be triggered if there is not enough space, not in full desktop view. As a typographer, the example screenshot is painful to look at. 3 posts with just one or two lines each that are waaaaaaaay too long for comfortable reading. This was always a problem with a default IPS installations but now it was made worse, not better. If the user info remains to the side, it also improves the readability of the post content.