This might merit a more thorough treatment later, but I wanted to bring a conversation that's started at the tail of a very long comment thread about the prospect of moving to the Twig templating engine in Drupal 8, and what that could mean for front-end developers writing apps with JS frameworks like Backbone.
To give an overview of how this would look, consider two scenarios:
This is a pretty awesome framework: there are no duplicate templates to maintain, we get both dumb-client rendered pages and smart-client interactivity, and we get the full power of Drupal translation, etc. in the templates before they are served to the client app.
I think the only thing that would be required outside the WSCCI work and the Backbone module would be an attempt by core theme writers to limit to basic Twig syntax (where there is not a JS implementation, Backbone module or a Twig.js module could override template files/functions).
What do others think about such an architecture? Any other important aspects we should figure in?