Can we please stop calling Unity/Unreal "free"? Unity still sells a Pro version, and Unreal takes a cut of revenue after a certain amount of $ earned. I'm not arguing against either model, and it's GREAT for hobbyists, but these engines still cost professional studios money.

The salient point is the barrier to entry. The fact that they still have some form of revenue related to the engines doesn't elevate the up-front cost any and the royalties (where they exist) are structured in a way that cannot prevent them from being a viable option for indie studios. The engines will be making the benefits of new graphics APIs properly accessible to indie studios in all the ways that matter; it won't be a AAA-exclusive thing.

(And professional studios don't have to license the ancillary tools and services and source code access of the Pro editions in order to ship a game.)