What I envision is simple themes in course settings (similar to what Blogger allows) or in the rich content editor. With HTML 5 and CSS 3 this should be possible, http://www.alistapart.com/articles/more-meaningful-typography/ (hint, hint). Keep the themes simple so they are accessible. The area that I would really love to see some improvements is the font settings. I would love to have some high quality font choices for body text and better font settings for line-height. I really hate the default font. It is hard to read. This was requested in the old community and it had 101 votes and much discussion on it.
Comments from Instructure on YEAR-MM-DD
After Discussion with our Engineers we are marking this idea as complete. Some of your requested features have been implemented and some have not:
Thank you for your feature idea. Please check out the new Theme Editor currently in Canvas Production Release Notes (2015-08-08). The new theme editor does not allow for font selection, but it does provide color personalizations as you suggested. For usability and accessibility reasons, we don’t plan on adding the ability for users to pick their own custom fonts to the Theme Editor though.