Hmmm...In detective work, they say 90% of the time the most obvious answer is the correct one...
It doesn't make any sense to me, that this tweet is in reference to a 'FAN FILM.' Especially considering that cease and desist letter the last Fan-film 'ALIEN: IDENTITY' received when she was supposed to play NEWT in that...
Think about it! If you or I had received that cease and desist letter, wouldn't we take that letter as a giant red-flag for us NOT TO move forward playing this character, in something else Fan-made? I'm sure Carrie Henn would be thinking the same and she wouldn't do so without some sort of direct permission, communicated from FOX.
She would probably be able to say so if she
was going to play NEWT for a new fan-film, on Twitter. And anyone
making a fan-film like that, would also want to receive a cease and desist letter
before taking a huge risk like that, given the issue with the last one, right? So these fan-filmmakers and Carrie Henn would want to know if they simply couldn't do it, before they move into production, risk getting shut down, or sued, after spending all kinds of money on a Fan film - given the circumstances. It really is quite soon to just assume ALIEN 5 isn't happening and Fox no longer cares so that last letter can be ignored....
'Fan-filmmakers' would otherwise want for, and encourage Carrie Henn to shout out on social media, every which way possible to say she was gonna play Newt in their fan-film, in order to generate interest and probably crowd funding.
With all these movies planned, green lighting a new game or series of books/comics
NOW seems logical enough, but we havent heard anything about that yet. Considering that we know about all these movies being planned and have heard nothing new about games and books... No. I'd wager, this has something to do with what we already know. Which is: they are making new alien films that plan to continue after Aliens, and Hicks survives, leaving Newt's fate up in the air.
I say Ridley Scott is looking ahead - that's the way that guy thinks - he and Fox do intend to produce A5, and to ultimately tie everything together... Unless there is something more apparent, I deduce that this looks like it confirms she has been contacted about doing ALIEN 5! ... At least, to me anyway!