The Government just released Regulations amending the age of dependency from "under 19" to "under 22". However, the changes will not come into force until October 24, 2017. As such, any applications made until that date will continue to face the current definition of a child being "under 19". Nevertheless, this opens up opportunities for those who were unable to include children as dependants to sponsor those who might still be under the age of 22 when the Regulations take effect.
The Full-Text of the Regulations can be found here.