YouTube will officially be shutting down its Youtube Gaming app on May 30, 2019, though the fate of the application had already been announced last year.
Regarding the transfer, Youtube’s Help Page mentions that subscriptions can be merged to main YouTube accounts, although saved games will be lost. The post also assures users that gaming content will still be available via the Gaming homepage.
According to YouTube, when it launched back in 2015, it was meant to improve and grow their live streaming specifically tailored to gamers. The app was able to experiment with a few new features such as the Dark Theme and Channel Memberships that were eventually implemented into the main platform.
With Google Stadia coming at some point in the future, Google may be trying to leverage YouTube to grow into its Stadia business.