I think it's true that the e-ink ereader is a minority device. Most readers use paper. Most ebook readers use phones. A lot use tablets. Enough use ereaders that the book vendors still sell them.
It's an excellent minority device and those of us who use them tend to be a bit fanatical about them. When someone in my retirement home tells me they prefer reading on paper I tease them about their 15th century reading habits. Not that it does any good but my fanaticism has to have an outlet.
So yes, there are and will continue to be reviews.
It's a sad thing, to me, that the blogs that focus on ereaders have declined. Those that focus on reading seem to be doing well. But there are still enough good ones that focus on ereaders that it's okay. And their decline seems to have levelled out in the past year or two.
Barry