Apple Watch developers have long been requesting for Apple to enable third-party faces, and it seems that will finally happen soon.
At present, Apple only allows its own watch faces to be used on its Watch lineup, though there are some from companies such as Disney and Pixar, but those don’t really count as third parties because of Apple’s deep ties with them. Even if an Apple Watch developer has a great watch face concept, there’s simply no way to submit it to Apple.

The feature might be rolled out alongside watchOS 5, which probably won’t come until much later. The most recent version of the operating system is watchOS 4.3, which brought a number of features and improvements, such as the ability to control the HomePod or music on an iPhone, an updated Siri watch face, and others. Version 5 will probably be a major update with lots of features, and the ability to choose watch faces from third parties will certainly be a nice bonus.