Previewed at WWDC, launching in the fall.
Apple Quietly Releases iTunes 12.6.3 With Built-In App Store
Apple is making this version of iTunes available because "certain business partners might still need to use iTunes to install apps", but the download is basically available to anyone looking to reinstate the functionality that was removed in iTunes 12.7.
If you've already installed a newer version of iTunes, you can download this version of iTunes on your Mac, PC 32-bit or PC 64-bit and run the installer. After installation is complete, you can continue to deploy apps with iTunes. You won't be prompted to download new versions of iTunes after you install this version.Installation packages for Mac and PC (32-bit and 64-bit) are available for download on the support page. After the installation, most users will need to rebuild their iTunes Library. To do this, hold down the Option key when the app launches and in the dialog window that appears choose "Create Library...". Give the new library a name that's different to your existing library, and then migrate over your albums using the Add to Library... option under the Files menu.
Apple released iTunes 12.7 in September and said the new version was designed to focus solely on music, movies, TV shows, podcasts, and audiobooks, which was the reason behind the removal of the built-in App Store. Following the change, apps and ringtones could only be downloaded on an iOS device.
This special "business edition" of iTunes includes compatibility with iOS 11, iPhone 8, iPhone 8 Plus, and iPhone X. It's not clear how long Apple will offer iTunes 12.6.3, and the company does not provide technical support for this version, but for those who want the functionality it could be a useful makeweight until Apple comes up with an alternative solution.