It doesn't really place any hard limits other than reserving the `children` key on attributes as a spec feature rather than an implementation detail. A 3rd-par

It doesn't really place any hard limits other than reserving the `children` key on attributes as a spec feature rather than an implementation detail. A 3rd-party factory can still break the `children` attribute out into a separate entity in their internal implementation. All it does is make the interface to the transform messier, by surfacing internal performance-related implementation details of React. This is code smell and I'd call it a syntax regression, but it shouldn't cause any severe limitations on what you can achieve. Personally I'll still continue to use JSX transforms with my non-React code once this lands. It's a great syntax.