Support can always come later, seeing that we are discussing a hypothetical future. If Nintendo sells at the current rate but the bigger two fail to sell more then 1 million in the first year, third parties would have no choice. Not saying I think it would happen, but it could.
That's a pretty big leap of faith. We're assuming that third party companies would switch projects from Orbis/Durango to Wii U just because it's selling when many studios would have to make concessions to get their games running. We're getting off track now but it's pretty serious.