Multiple questions there.
Read the official announcement carefully:
September 30, 2022, at 00:00 (PST) we will start migrations of Groovy device DTHs as well as SmartLighting and SevereWeather SmartApps, two of our most popular Smartapps built on Groovy. On October 15th 2022 certain functions of the legacy developer IDE, such as the creation of new DTH’s, Smartapps, and debugging tools will be removed from the SmartThings platform and will no longer be supported. After migrations are complete, this means that devices and automations previously using Groovy will now exclusively operate with our latest hub and cloud technology.
A) we don’t have an exact date for when any groovy smartapp will stop working.
B) Smartlighting IS going to be migrated to the new platform, but we have no details as to what that means exactly or whether it will have all of the same features that it does now.
C) they are allowing for the possibility that the smartlighting migration could start as early as September 30th, but again, no specific timeline has been given.
D) they have not said anything one way or the other as to whether the region locks for the new SmartLighting will be the same as the ones for the old.
E) They have not said one way or the other as to whether smartlighting automations will count towards your routines and automations limit.
F) it sounds like it’s possible that we will lose the ability to add more groovy smartapps before our existing Groovy smartapps stop working. That lines up with something @rboy said he and other developers have been told quite a while ago. But again, no details.
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So there are just a lot of unknowns except that there will be something called smartlighting on the new platform for some people. 