Apparently, since Michael Arndt left the Star Wars project and J.J. Abrams fully took control, things have changed quite a bit according to The Hollywood Reporter. When Arndt left, it was said that Abrams was taking control due to time issues, but they are saying it was more about a difference of opinion.
Originally, the new trilogy (and first film) was going to focus on the children of Han and Leia, and Luke and... whoever. But now, Abrams is looking at Episode VII to be a sort of send-off for the original cast, keeping the focus on Luke, Leia and Han, then passing it off to the kids as they move to Episode VIII and IX. George Lucas was originally on the side of Michael Arndt's script, but since he no longer has anything to do with the franchise, that really doesn't matter.
This is the reason we've been seeing a lot of older actors in the rumors about actors Abrams has taken meeting with, from Benedict Cumberbatch to new names now, like Hugo Weaving, Michael Fassbender, and Adam Driver. A few of the bigger roles originally planned for twenty-somethings have now been changed and/or replaced by forty-somethings.
They are still working out the final details of the script however, and Abrams is said to be meeting with "everyone." This includes the rumor from the other day about Jesse Plemons, but unfortunately doesn't come with any roles attached to any of the meetings except for Hugo Weaving and one other role. Weaving may be considered for the part of some sort of Imperial Commander. The other role is the most interesting bit of gossip: "20-something female actress who is either of mixed race or black" who is Obi-Wan's daughter or granddaughter.
I'm not sure what how I feel about this news, but it's early in the development, so we have plenty of time to get upset later. Personally, I'd rather them move on from the original cast and focus on the new characters in a new story and stick to a "send-off" for the original cast in the form of cameos. They still could though, there is nothing saying that all the surrounding cast has to be made up of twenty-somethings just because Solo/Skywalker kids are. The main thing to take from this is that Abrams is meeting with everyone, so all the rumors of actors being eyed are probably true, but obviously won't all pan out. I do like the idea of Obi-Wan having a kid or grand-kid mixed up in all this. They need to start moving forward on this project soon, so details should get more accurate throughout the year.