โIfโ makes no sense here. It just works as it always has. You canโt uninstall WebKit from iOS. If you install Firefox and Firefox is now using its own renderer, that does not uninstall WebKit across the OS. Nor does it install a browser engine for apps to use.
All browsers are WebKit in iOS. Although this is going to change in this new version, the ability to add it to your home screen and function independently from Safari is what was being revised.