But a few have remarked to me that looking more closely the hand/arm look too small to be Hamill's (it looks like a woman... THAT could be Carrie Fisher), while what you suggested was a shot of Leia I rather think is a shot of the young female lead receiving the lightsaber.
It could make sense.. .Leia got post ROTJ a lightsaber from Luke which she never trained with/used, but as she suddenly senses the Force in her daughter and sends her to find the reclusive Luke to convince him to train her/return to Leia because the force is "awakening", she gives her the lightsaber That would be very SW... if the lead/jedi trainee character is the girl, then the "quest giver" figure (ie: the Ben character, if you wish) needs to be her mother or a mother figure, sending her to "Yoda" (Luke). This would also be a replay of ANH to an extent, with Leia sending someone on a mission, with R2.
It wouldn't be too mythological for that figure to be a man, for a girl hero. It would also make sense for Lucas to have toyed with the idea of a female lead for the last trilogy, as the Hero's journey and its archetypes are different for women, and unlike the male ones with the OT/PT, he had not exhausted them yet with Leia and Padmé.
Plausible. But, if as you say "Leia got post ROTJ a lightsaber from Luke which she never trained with/used" why would she have a mechanical hand? Loss of limbs seems to generally occur in the SW universe during lightsaber combat. Also, is it likely that another Skywalker member loses their right hand? (As I type that question, I think the answer is that's it wouldn't be out of the realm of possibility.)
I just think that with the voice-over speaking about Anakin as they show Vader's mask, it makes sense that as Luke is talking about himself the scene would show himself, and the same with Leia.
All true, except this is a trailer - the "voice over" is most likely on-screen dialogue lifted from another scene. My feeling is that the shot with R2 and the person with the mechanical hand touching him isn't truly related to the dialogue. I think they edited it that way because showing a shot of someone with a mechanical hand made a good visual symbol about Luke/Vader's history. I don't really see why Luke would revert to sort of prosthetic when he's got a more advanced bionic hand that looks just like a real one in ESB/ROTJ.
I don't think it's Leia either who touches R2, though I wouldn't be surprised she's the hand that hands the girl the lightsaber. If not her, that'd be Luke, no matter how small/feminine the hand feels. But the robotic hand shot with R2... no idea who that is, but normally that'd be a Skywalker (or Solo), or the villain. I guess the girl, who sure looks like a proper daredevil, might have lost a hand already.. which would be...not exactly promising about her character from Luke's perspective..
I'm really curious how they'll handle the "apprentice" this time around. They already got the "proper apprentice" with Ben in Jedi, and two variations of recklessness/eagerness/arrogance - one that leads to doom, the other who manages to find his way to wisdom.
I wonder.. if she's Solo's girl, might we get the apprentice who doesn't think much of the Jedi nor want to become one?