Is Natural Earth (the site) dying?

Yes, the Issue tracker on Github has taken over as the primary method of filing bugs and questions about Natural Earth. The corrections system and forum on the primary site were always a bit clunky, and the new system has better visibility (and less SPAM to deal with).

Natural Earth's focus has always been about the big picture, and those details aren't expected to change much year to year. It's still an active project.

It looks like emails were bouncing to [email protected] because a quota was reached. I've fixed that in the site admin. I can still login and post to the forums, send me more details of your problem via email.

I leave you with a JFK quote:

“And so, my fellow Americans: ask not what your country can do for you – ask what you can do for your country.” The same goes for Natural Earth. If you see something wrong, please lean in and fix it.

Although there haven't been any major releases, the data is maintained at https://github.com/nvkelso/natural-earth-vector - as you can see in the list of issues there, there has been updates and comments in the recent while.