However, until Pro/E or Catia is available for Mac, "serious" engineering work will always have to be done on PC
Siemens' NX for Mac (formerly known as Unigraphics) was released one year ago next month. And their clientele is every bit as impressive and widespread as Catia's.
Even if AutoCAD ports the application(s), what would people run it on? iPad? iMac? Overpriced and outdated Mac Pro?
As I noted a page or so ago, I've been running Solid Edge on a 3 year old box stock iMac without any problems. AutoCAD should be flawless on any recent Mac. [edit] Almost four years ago. Photo was taken 10/2006.

Extreme low res video of above casting being manipulated. 27 MB file with no artifacts or lag whatsoever.