The goal of Shumway is to be able to run all Flash content.
Adobe Flash, and the Adobe Flash Player as it exists now, is the result of
a full-time team of 50-60 engineers over twenty years, spanning 20 versions
of the player. Shumway has around 5 full-time Mozilla employees working on
it, and a few community contributors (including me).
Right now, we're focusing on the demos listed on the Shumway home page, and
making sure that those are correct and performant.
Additionally, while HTML5 video/audio is available in modern browsers, the
multimedia APIs used by Flash internally expose more low-level details
about rendering, and it will require changes to the HTML5 specifications,
or require us to implement video/audio ourselves in JavaScript. This will
take some time.