As much as I love Dorothy, she's not a princess (Ozma is though)! Also, even though it's been almost 72 years since the first film it's too soon for a remake. Dorothy is still Judy Garland and who knows when that will change....LOL

I know some non royalty characters make the line up, and the wizard of oz is a good enough story to have a shot, but Dorothy is too iconic a character for Disney to make her their own. Even if they did their own version, and even if it was amazing, it wouldn't surpass years of love for the original movie, and I don't think they'd put a character who was second in the public's eyes into their line up. I don't think they'd want one of their line up to be a character people considered the second best version, because no matter how great she was it would drag down the line up's rep, since all the current members are the iconic movie versions :)

Don't even think about messing with what is arguably the most classic movie ever made.