Is there any place where i can check current status and plans for -preview flags?

[ryuukk_]

I'm interesting in that as well, i use 
``-preview=rvaluerefparam`` in all of my projects, i can't live 
without it, i would love to know about its state and if it'll be 
merged as a official feature (hopefully not removed lol), i'm in 
the process of simpifying all of my builds scripts right now, 
removing one more flag would be cool