"Haven't seen a multifunction device yet with a battery life in the two week and 10,000 page turns range. I'll look at one when I see that."

I don't see battery life as an issue. I can carry spare (quite light) batteries for my cell phone, and/or a solar charger, and/or charging cord. On the PCT this year, I was never 2 weeks away from a next-resupply point, but that of course depends on the particular trip.

It is true, however, that if I'm feeling on a tight power budget, I might be less willing to read if I fear that as a result I might later be unable to make an important phone call or take pictures or whatever. For my particular trip, it turned out that I didn't have the time and energy to read much on the trail, I mostly read books in trail towns, where I could recharge. It was great, however, to have the book reader functionality included at no extra weight cost.

Per previous, I don't suggest this as a panacea but as an option that might be right for some folks.