We've seen a couple apps get around Apple's restrictions by going with manual installs with the help of the new version of Xcode, which no longer requires a paid developer account. Over on the Kodi forums, DanTheMan827 shows how to install the Cydia version of Kodi on a non-jailbroken phone using a similar approach.
The basics here are pretty simple. You'll take the Kodi Cydia file, create a special profile, then go from there. It's essentially repurposing the Cydia app and installing it manually using Xcode 7, which isn't anything new, but the fact you no longer need a developer account makes it more accessible. Head over to the Kodi forums for the full guide, or check out iDownloadBlog's video guide linked below.
Mac OS X - iOS App Signer - Install Kodi without Jailbreak [Kodi Forums via iDownloadBlog]