Wanted to reference this here in case people didn't see it. We've got https://drupal.org/project/webcomponents module able to go straight from polymer templates to display modes to field UI to rendered output. This completely by-passes the traditional tpl / template file workflow and allows front-end to dictate design to backend (instead of in Drupal where it's usually a mish-mash of both). It's also by-reference so updating your templates sees them updated in Drupal.
Anyone play with workflows like this / interested in joining efforts to make it even more robust? I can see this eventually eliminating a lot of arguments of panels vs DS vs templates vs wysiwyg body field if the template engine is completely separate from drupal.