> I worry this will suffer from the same lack of developer interest as the AVP did

Pretty sure that developer interest is not to be a problem. The Duo will sell more units in a month (or less) than every AVP ever sold.

Apple told developers in June at WWDC to not assume fixed screen sizes. Well-written apps will work on any screen size thanks to Apple's APIs.

Some apps will need to be tweaked to take advantage of some Duo features no doubt, but I suspect that's not going to be a deal breaker.