Although I would recommend keeping the "192 comments" link at least as large as it currently is. That's probably the 2nd-most tapped-on link (after the link to the source itself), and it's fairly difficult to aim correctly on mobile. Making it even smaller will make it harder to tap.
I always go to comments before clicking on the article link. While I'm reading, post can go away from current HN page and it is hard to locate it again.
Ps. iPhone4 is not compatible with new layout at all.
https://en.wikipedia.org/wiki/Fitts%27s_law