I'm finding myself increasingly interested in getting a "supplemental" PDF of my dead tree books. I've started doing more and more game prep on my tablet and it is really annoying to be all snug on the couch with tablet in hand, but have to rifle through the stack of books sitting on the floor next to me or, worse, discover I left something upstairs and have to run and fetch it. I really never thought I'd hit that point.
I hope they decide a small, black coffee. A $1-$1.50 wouldn't change my buying habits much. But, a $5 tag for the PDF would drive my business towards Amazon, etc. even more than it already is. Currently, I get a few books from a brick and mortar shop and mainly go to Amazon if I'm ordering multiple books at once. I'm quite certain, though, that I'd start thinking "you know, if I got this from Amazon, I could get the paper and PDF for the same price as just the paper, here."
On the other hand, if authorized game shops had the rights to validate purchase of the paper book and WotC would open the PDF online, it would make the FLGS much more attractive. Unfortunately, 75% or more of the LGS I've seen are sole-proprietorships that wouldn't show up as trustworthy to WotC.