Pure speculation, but I note the Nook Glowlight Plus (7.8") is out of stock (only refurbished units are now available). This is what happened to the Glowlight 3, right before the Glowlight 4 came out (new GL3 units never came back). Is it possible that the new Glowlight is a new 7.8" replacement? In time for Mother's Day?
I also just got a notice on my Android Nook App — something about now playing audio books directly in the app. (I don't have audio but I think that's new.) I wonder if the new Nook will finally use its Bluetooth feature for audio books (as they speculated it would do with the Glowlight Plus (7.8")? Maybe the "-A" stands for "audio?"
As I said, pure speculation.