I first asked this question on HN 688 days ago https://news.ycombinator.com/item?id=9476097 and since then, email newsletters have only gained popularity.
...Calacanis has gone all in on Newsletters with Inside.com, TheHustle.co newsletter is disrupting news for millennials, and Ben Thompson's paid Stratechery letter is making the 1,000 True Fans model work.
It seems that email will just keep on going.
Disclosure: I run Letterlist.com, which focuses on newsletter discovery. I ask because I'm obsessed with inbox publishing.
My Quora Digest
Money Under 30 [0]
Strength Sensei [1]
[0] https://www.moneyunder30.com/
[1] https://www.strengthsensei.com/