I really like this navigation model - it reminds me a little of the Panorama control [1] that Windows Phone attempted or the column-based, horizontally scolling UIs of the infamous Windows 8 Metro apps [2].
Sadly these more creative approaches seem to be forgotten in place of lazy hamburger menu/pages with back-stack style approaches.
Good job. I hope you expand on it more. Maybe consider a browser extension to convert other comment sections that arent hn. I always thought replies to parent comments shouldn't be prioritized over top level parent comments and this layout pushes that idea.
Probably from users of more classical UI, this feels really unpleasant to me, like putting a tshirt backward. (not that it's a bad UI or anything, says more about me than your website)
Interesting idea, but using columns for nested threads is too clever by half. Have two columns, one for the main page, on for the thread, and display nested threads normally.
Sadly these more creative approaches seem to be forgotten in place of lazy hamburger menu/pages with back-stack style approaches.
[1] https://www.minddriven.de/wp-content/uploads/2011/02/wp7_pan...
[2] https://cdn.mos.cms.futurecdn.net/ytfp8btYCkR2rCpW9WS9u3.jpg