Just had the most incredible thought.

Yeah, not only that, but both twins had informal N7 training from Alec in addition to their Alliance training. They're much closer to N7s than Ellen

I think that parts a given.  So here's my idea.  She's the MB.  She also came out of cryo to assassinate Jien Garson and then returned to it.  Ok, I'm kidding, but it would be a hell of a twist and explain why Jien's murder was wrapped up in the Ryder Family Mystery.

Maybe she is being kept alive for the next story arc.
After ME:A3 is finished and the Sara/Scott story is done we zip 100 years into the future where Ellen is finally cured and becomes the new protagonist for Mass Effect 7.

The thread title advertised "Incredible".

Personally, I'm extremely satisfied with the Ryder twins.  Also, why would potentially curing Ellen's disease and her waking up just now after everything that has happened (possibly not even realizing she's in a different galaxy 600+ years in the future), this is under the false assertion that she is an N7 which she is not... she's not even a soldier, automatically negate Sara/Scott Ryder?  She wakes up after being in cryo long enough her children thought she was dead prior to launching the Initiative and all of a sudden she says "okay, kids, back to day care... momma's taking over."  And then what...?  She blasts into space with nothing but the will in her fingertips and wipes out the Kett Empire throughout Andromeda?

Sara or Scott Ryder just defeated the Archon, took over Meridian, teraformed potentially four colony settlements and forged alliances throughout Heleus with multiple factions.  Why would they suddenly be too out of place and cast aside?  That doesn't make any sense.  Also, even if Ellen WAS an N7, why do we NEED that for Mass Effect to continue?  Frankly, I thought having a young, inexperienced character we mold was a breath of fresh air from an established super-soldier space marine.  And this is from someone who LOVED Commander Shepard.

I truly do not think in any way, shape or form this is what the writers are going for.  Let alone casting aside who we play as the entire game and making our personal choices and favorites null and void, it boxes us in to a specific single character as one gender and a predefined identity, personality and experience.