As ereader replacement, you can grab any kind of tablet (i suggest you screen aspect ratio 4:3, and not 16:9 or 16:10, much better for reading), maybe a cheap one (you must use it only for reading), installing a good ereading app (my preferred one is pocketbook, but there are a lot of apps, free or not, on google play or other android markets), put it on night mode (black screen and white characters, there is another mode on some apps, black character on papyrus screen, but i realy don't like it), down backlight as you prefear and... bingo
A tablet is more versatile: pdf, cbr/cbz better than an ereader, external estore apps for ebooks such as kindle, kobo, tolino, and so on.