Will Dragon Age: Origins ever be available for mac again?

If it's not on Origin, I don't think it will be easy to find anywhere else. Maybe you can find some sealed physical copies somewhere, but that will probably be expensive.

As an alternative, you could either install Windows on your Bootcamp partition or play the game on the Wine emulator. https://appdb.winehq.org/objectManager.php?sClass=application&iId=10457

It's available still.  Use google to search. I found a copy that included Ultimate Edition plus DA2 for $40 on gamersgate