FSCopyObjectAsync is Deprecated in OS X v10.8, Now how to display progress indictor for file copy operation.
My answer assumes you're talking about showing the progress of a single file being copied.
Yes, "FSCopyObjectAsync" been deprecated but it's not gone yet.
And as you have discovered, Apple has not yet provided a useful replacement for the functionality that will eventually be removed. I suspect (but do not know for certain) that when the new functionality comes in, perhaps for 10.9, it will be delivered in the "NSFileManagerDelegate" protocol for delegates to make use of.
To make certain of that, Apple needs to be aware there are lots of developers need this. File a bug report at http://bugreporter.apple.com -- it'll likely be closed as a duplicate, but every vote counts.