Yes, they say that. But, you can still do many things (faster, easier, more reliably, only) in the Classic App. They should work harder on fixing that before they “phase it out”.
I suspect you can do the same in STHM in the new app (*).
The key thing to getting Alexa to announce is to use Echo Speaks (**), and if you can hook up an announcement in STHM as trivially as it is in SHM, then it should be easy to accomplish this in the new app.
(*) I can’t test that because you apparently can’t use SHM and STHM at the same time, and I’m not going to discard all the working alerts in the SHM on a hope and prayer that they’ll eventually work the same in the new app.
(**) Echo Speaks is a Groovy SmartApp, and Groovy support is also going to be phased out. Hopefully, SmartThings doesn’t discard their massive competitive advantage in their existing rich existing ecosystem.