From face-to-face meeting on Web Animations, as discussed here. There is now a CSS-SVG Effects Task Force activity on this.
SVG Animation (based on SMIL) and CSS Animation offer some similar features for animating Web content. Harmonising these two technologies has been considered on a number of occasions but a path forward has yet to be established. In response to a feature-by-feature comparison of the two technologies the question was raised, “What are the animation features required, prioritised by use case?” (Meeting minutes which lead to Action-48) although a closely related question was, “What would it take to make CSS Animations achieve feature parity with SVG Animations?”
It has taken time, but by now CSS and SVG are on the same team, which is kind of a precursor to make the specifications well-integrated as well.