That depends if that is a firm date from ST or one where it is subject to change. Right now, it looks like both groovy custom device handlers and smartapps will cease. You can watch the first post in the following thread as they have been updating the dates there as needed: The end of Groovy has arrived
Another user posted a message from Maddie so I will let you look at it and follow their recommendations: [RELEASE] Lock User Management (LUM)