Okay, I'm a whole lot more willing to think that Nikki is going to become canon.
Two reasons: one, the connection between the "eye" symbol in the box that Nikki found and the tattoo in Gemma's vid.
And two, this information from
the Wired story on LG15:
As Bree's universe expands, each new character will have his or her own vlog. Flinders can't write and film them all, so new writer-directors have been hired and paired with actors playing the new characters. Unlike television, where writers sit in a room and come up with a single script, the Lonelygirl15 team comes up with a general plotline and then sends its writer-directors out to produce independent but interconnected videos. All the characters, in essence, have their own show.
I put the most relevant portions of the quotation in bold, BTW.
Looks like Nikki's vids may very well be among those "independent but interconnected" videos the creators are blessing.
I do have one thing to say to Nikki, though:
Hon, you need to pull up your shirt. All that cleavage is distracting from the storyline.