The black-white e-readers are doing a great job at a great price point. Color would have to have a similar battery life, resolution, and only an incremental price-increase to be appealing.
They're not doing that great. A4 (or letter) sized ereaders right now cost $800+, have a resolution of about 200dpi and only a few shades of gray, so they're practically monochrome. For that amount I can print thousands upon thousands of pages at 1200+ dpi on real paper which I prefer. I thought about it and bought a laser printer. When the technology matures a bit more, I'll be waiting. Less eagerly every year though, as I've been waiting for affordable large ereaders for 10+ years now. And I'm seeing a shift to tablet-like device features which I'm not fond of.
That sounds like an interesting idea - now I want to print ebooks in my favorite font size... but that feature is locked behind DRM. Still, for webnovels it may be viable.
Are talkinkg about the tiny e-readers locked into Amazon's ecosystem?
There are tons of e-reader out there, but if you aren't searching it's likely you will only know Kindle. Kobo is also very popular, but there're also PocketBook, Nook, Likebook, Onyx Boox, Bigme, etc.
There are many others. Kobo for example doesn't lock you to anything and you can pretty much do whatever you want with the Linux on them.
Kobo is 10" max which is too little for me.
Locked? Hardly. Connect the reader using a usb cable to a computer and it shows up as a drive you can drag file files on to.