Count me among those who love 1776 as is, and don't really consider it in need of a radical re-imagining. I've loved it ever since we watched the movie in fifth grade. Our teacher was a history buff who imbued in our class a huge appreciation for American history. I learned more about the Revolutionary and Civil Wars in that class than I did in subsequent history classes in middle, high school, and college. Seeing the Founding Fathers portrayed with humor, wit (sometimes using their actual words), and humanity was great, and I loved the songs.
I agree that Paulus is very hit or miss. Her track record with revivals seems a bit better than with new works. Hair and especially Pippin were among my favorite experiences in a Broadway theatre. Finding Neverland was boring, though Porgy and Bess was extremely underwhelming compared to the full operatic version. (I'm looking forward to the broadcast of the Met's production, which I didn't get to see. I loved the SFO's production that aired a few years ago.)
Having seen a few clips of all-female or mostly-female casts on Youtube, my main concern is that this music just doesn't really work with female voices. The harmonies and melodies were written specifically with male registers in mind, and it loses something when you don't have a booming baritone singing "The Lees of Old Virginia" or "Molasses to Rum." I can imagine the latter being sung by a black woman, however, to bring out an interesting subtext, but I feel I'd still miss John Cullum's terrifying take in the film. The harmonies between John and Abigail on their duets would also lose something, as would the refreshing quality of Martha's "He Plays the Violin" in a male-heavy show. I wouldn't mind colorblind casting like the Encores concert (Nikki Renee Daniels was my favorite thing about that concert).
Paulus is an intelligent director, though, and I'm curious to see what she does.