Is @me.com or @mac.com email forwarding being supported indefinitely?
Does Apple have any date for when @me.com or @mac.com will stop forwarding to @iCloud.com ?
.. or is this being supported indefinitely?
email / iCloud-OTHER
There has been nothing announced that would indicate they would stop forwarding @me or @mac emails to @iCloud. Apple owns all those domains so there is no reason to believe they will stop doing so.