On very large screen, there can be a lot of whitespace outside of the columns that is simply not being used. A potential use for this that would be to move specific content items outside of the content block entirely and put them there, where they would both be more easily seen and also result in less clutter.
- Infoboxes (would likely require use of an extension to manage them, or similar), and other content-defined navigation
- Table of contents
- Images (appearing on side according to left|right floats, unless they don't fit?)
To mak this work, it may be necessary to also lose the second sidebar (right-side) as it currently works and consolidate back into a single site-nav sidebar on the left like monobook (with the possible exception of page-specific tools). This would clear up space on the right for the infobox and images.
The table of contents could then either be moved into the left sidebar after the site nav (eeeh), or remain in the content until scroll-past, and then remain as a sticky left sidebar after passing all of the regular left sidebar? Making it sticky would cause issues with left-floated thumbs, hoever, as we would also likely want to be moving these images here, non-sticky.