There isn't a way which the WDN would provide to show all the links at once.
This topic was discussed quite heavily before we arrived at the current design. Here are some of the topics discussed - and reasoning behind why the WDN decided to go with this design:
If you have more than 5, the navigation gets trimmed to 5 to provide an evenly distributed left hand navigation.
With an unrestricted amount of subordinate (second level) navigation, some navigation might be pushed 'below the fold.'
The idea was to give the users a hint at the sections which are beneath the primary section of the website.
And for some, this limit has given them a reason to seriously look at their site's navigation and redevelop it so their site is better organized and doesn't provide an onslaught of links to the user.