@cobalt-jade @ghost93
On the idea of Meryl Streep being cast as "Aunt Andrew" (I.e. as Uncle Andrew) or as Old Mrs Lefae in the upcoming 'The Magician's Nephew' movie. I would welcome having Meryl Streep as Old Mrs Lefae. Uncle Andrew is a harder sell, as I'd prefer to keep the character consistent with the book. (Though I would prefer this to having a female Aslan - but the good news it that the 'female Aslan' rumor looks like it has less and less substance over time).
At first look "Old Mrs Lefae" would be too small a role for an actress as talented as Meryl Streep, but they could expand the role. A flash back when Uncle Andrew is describing the events to Digory could have more detail. (Also, her role as Aunt March in Little Women only had just over 7 minutes of screen time, so she does not have to be in every scene).  Given Uncle Andrew says that she was locked up in Prison, you could potentially have a comical flashback (contrasting with Jadis's conquest of London later in the movie).
I do not think Uncle Andrew would require many changes if he were cast as an Aunt Andrea. (Admittedly, it is not going to make sense for her to be attracted to Jadis if she is a woman.) Correct me if I am wrong, but I think Uncle Andrew's selfishness, narcistic tendencies, alcoholism and eccentricities would not need to change at all if they altered his role to be a woman rather than a man. Both men and women have failings in all these areas. (For instance, think 'The Devil Wear's Prada' for a role in which Meryl Streep played a character with several similar character traits.) 
So, either of these could work.

But why would Narniaweb's source tell them Streep was in talks to do Aslan when she was really in talks to do another character? From what I understand, they specifically asked for clarification in that area. 

@davidd I love the idea of Meryl Streep as Aunt Lefae - and she has played similar small cameo type roles in other films, so I don't think it's beyond the realm of impossibility!

@col-klink , I can't speak for everyone else, but from my perspective, this current line of discussion is wishful thinking. I would LOVE to see Meryl Streep as Aunt Letty or Mrs. Lefay. Aslan, not so much.

I do have a question for other people who have seen more movies than me (which is about everybody), has Meryl Streep ever done a British accent? And if so, how'd she do? 

@fantasia 

the only movie I can think of where she used a British accent was for ‘Iron Lady’ where she played Margaret Thatcher. 

see https://www.youtube.com/watch?v=xxcsGcV8s9g

She is famously a master of accents

@davidd yes, and shecwas very convincing