Agreed, and thanks for the feedback. My initial (and possibly very naive) assumptions are:
1) If readers are permitted to TTS RSS feeds then human recordings "should" also be legal. (Not that I actually expect the laws to be consistent or make sense.)
2) This would be one of the first things I looked in to if I pursue this idea.
3) "If I want TTS I can do it myself." This is certainly true, but the options I am aware of do not provide a seamless interface. For example, would you want to do it yourself while driving in traffic?
It seems like you have a pretty good idea of what you want to do. That said, assumption number 3 is not entirely true. Pocket (which is already widely used) has TTS tech integrated and it's really easy to use.
I could see the value so long as the articles are narrated by a human. A condition that, like you said, seems to have a lot of strings attached to it.
That said, with actual human readers this could go very well. I would like, though, to point out the possibly insurmountable issue that pops up every time someone has an idea like this: copyright.
It is a sad state the current copyright laws are in, and a good example of that is how they interfere with the creation of awesome services like this one. IANAL, and all that, but I strongly suspect you'd get hammered down hard if you didn't get explicit permission from the authors of every single article you broadcast.
So seriously, speak with a lawyer, please, before taking a single step with this. Perhaps you can find a workaround, or someway to do this regardless. Or maybe not. But at least you won't drown under a mass of lawsuits.