Its been two years since the Kindle Paperwhite three release, so we are due an update. There is a picture and information leaked, via a Chinese retailer, of a possible Paperwhite coming out. Information is sparse, other than a water-proof device, a flush display, the same 300PPI and what appears to be, again, a six inch screen. This is speculation, and I can be very wrong, but I think the leaked information is generally correct. The information provided is consistent with Amazon's strategy of keeping the six inch size and introducing small incremental updates.
The leaked information also noted two further more premium Kindle devices for 2018. One is a six inch e-reader - possibly replacing the Voyage - and a high-end seven inch one. Again, I think the leaked information could be right. Specifically, a seven inch Kindle - to replace the Oasis - may finally provide something to entice e-readers to choose a high-end e-reader over the Voyage and Paperwhite.