I think we have a long way to go to firm up what we're actually doing here, and what the organization should have as a remit. However, what may - to my thinking - exclude non-wikinews journalists is NPOV. I believe that any organization that is set up should adopt that as a core tenet.
I am not aware of the detailed technical differences between a union and a non-profit, but to me it appears that a union's objective is to represent its members' interests, a non-profit is to represent its goals. So, whilst you could set up a non-profit with the goal of representing its members that is putting the non-profit goals on shifting sands.
So, to consider the idea of including citizen journalists outside the Wikinews community, I believe the association with WMF should require an adherence to NPOV. This *will* exclude a lot of excellent reporters who write good editorial and opinion pieces. Is there any way we can be inclusive of these people if they clearly label online work as opinion or editorial when it doesn't meet NPOV? A key issue for me would be getting bloggers to work within the WN NPOV framework to produce an article then doing their opinion/editorial introduction to the "neutral" story.
Going back to what we call this, I tried all the http://www.wju.org (Wikinews Journalists' Union) acronyms I could think of at short notice. Only free one was http://www.upj.org - Union of Pajama Journalists. :)
Brian.