iPad mini is not a phone, and between 4.7 and 7.9 there are many mainstream phones and phablets, so we can't really generalize.
I think at this point it's all about iOS. Apple already started making steps to make it resolution independent. Developers will probably follow suit.
Out of interest, has anyone ever hacked iOS and put it on a non-Apple bit of hardware?
I always wondered whether iOS for iPhone on a 9.7" display automatically adjusted to look like an iPad, or whether Apple built a modified version of it for iPad.