where is all the speculation that she is going to be charlotte coming from?
i will admit though, it will be pretty interesting to see her character develop if she is in fact charlotte. i'd love to see her puella outfit (though im anxious it wont be what we're all expecting, and in turn wont be well received), why she made her wish, and what triggered her to become a wish. it would answer a lot of questions!
Well, as you said, it's merely a speculation. But noticing many details that may imply that the new magical girl /is/ Charlotte, they seem too many to be a coincidence? Kind of... We don't know what to expect, still, since it's just the design - regarding the fact that the creators are suckers for symbolism though, probably it's going to turn out that Nagisa is indeed Charlotte. The colour pattern of her outfit (cherry red bottom, pink top, brown details), the styling of her hair (pigtails and how the fringe's stylized too), her eyes - if you look at it that way, then you see it's quite heavily implied.
I agree with you wholeheartedly on the puella outfit matter tho, yup.