There are no plans to do anything about the whitespace in the display template. If you really don’t like it, you are free to not use the SuperGrid display template and just switch to the default one for just the display view.
The site shown last is a good example. The layout actually creates a very good column width, which improves the legibility significantly – making the articles easier to read than long texts in this fluid forum for example. So it’s a feature, not a bug. I won’t compromise on such matters of legibility. I won’t make things worse, not even when I’m asked to.