If the question is "what site in early 2018 most resembles HN of 2006", I believe the answer is Indie Hackers. Its community is open, friendly, genuinely helpful and focused on business.
It's not quite the same since it takes more of a pro-bootstrapper stance, but then again the HN ethos used to be more tilted towards frugality and truly early-stage companies than it now is.
Things will undoubtedly change as they grow, but IH is arguably the finest place on the internet for entrepreneurs.