Here is a reply to this concern from Stephen Heilner, that he posted in the "LDS Gospel Library iOS" Facebook group:
"Gospel Library 2.5 can run on every iOS device ever sold. This means the original iPhone, iPhone 3G, iPhone 3GS, iPhone 4, iPhone 4S, iPhone 5, iPod Touch 1st generation, iPod Touch 2nd generation, iPod Touch 3rd generation, iPod Touch 4th generation, iPod Touch 5th generation, original iPad, iPad 2, iPad (3rd generation), iPad (4th generation) and iPad mini. Not only do we support all these devices, but we support all major iOS versions on all these devices, namely iOS 3.1.3, iOS 4.2.1, iOS 5.1.1, and iOS 6.1.3. We are happy about this because it means everyone with any iOS device can have the scriptures and other church content on them.
"The downside to this full support of devices and iOS versions is that it has a disproportionally high development and testing cost. For a team as small as ours, it's difficult to sustain. Further, as we look at our usage statistics, we are quickly approaching the point where almost 95% of our active users are running on at least iOS 6.0. In the 5 years since the original iPhone was announced, the development environment and platform for iOS apps has matured dramatically. Yet many of the new features we can't fully embrace while still supporting all older iOS devices and versions. Finally, since May 1st, 2013, Apple no longer allows us to submit app updates that support iOS 3 and 4 devices. Given all the foregoing, it has become clear that it's time for us to make a change.
"Gospel Library 2.5 was our last release to the App Store that will support the current broad range of devices and iOS versions. We call it our "Sunset" release as all good things must come to an end. Gospel Library 2.5 will remain in the App Store, new content will continue to be pushed to it and you can use it as long as you please, but all our future development will be focused on a new version of the app, namely, Gospel Library 3."
Samuel Bradshaw • If you desire to serve God, you are called to the work.