I don't mind if they simply move to a new generation, so long as the actors are actually capable. I thought Daisy Ridley showed a lot of promise and, frankly, there is no going back. Carrie Fisher is dead and while they can bring Leia back for small parts, ala Grand Moff Tarkin, you can't build a movie around that kind of special effects. At least not yet.
But this trilogy seems to be following in the same tradition as the two other Star Wars trilogies in terms of casting. You pay for 1 real brand name actor to help out launching the first movie, and you give a bunch of mostly newbies or moderately seasoned others a shot at main roles. Here's the big correlation: Alec Guiness (ANH) = Liam Neeson (uggh Prequel) = Harrison Ford (SWFA). Star veteran actors playing starring roles killed off in the first movie of a new trilogy.
As for the less seasoned but experienced actors, Harrison Ford (ANH) = Portman (Episode I) = Carrie Fisher (Episode VII). Name recognition for all, experience for all, but few starring roles. Ford had a ton of roles, but nothing really starring before ANH. Portman had a few roles, including a turn as a child actress as a star, but nothing ground shaking, and Fischer's starring roles by the time Episode VII happened were 35 years stale with lots of minor roles and industry experience since. You could also throw McGregor into the mix as he had some experience before Episode I, TV and Trainspotting, but if you dive into it, it was pretty thin.
Finally you get the starring turn newbies. Carrie Fisher and Mark Hamill in Episode IV, Jake Loyd (uggh) in Episode I, Daisy Ridley and John Boyega in Episode VII. There is nothing new here. Losing Fisher hurts the pattern as Ford, Portman and McGregor carried on throughout the prequels, but I don't see it as make or break. Especially as they can fill her role with Mark Hamill if they really want to. Seasoned actor, few starring roles (and those long in the past), but name recognition.
Regardless, the stories will make or break this trilogy, and the story in Episode VII was passable. Was it ANH or ESB? No. Not even close. But it was better than the prequels and, in my opinion, Jedi, which I always felt was the worst of the originals by far. The seeds of Jar-Jar and the stupid battle at the end of Episode I can be found in the abomination of the Ewoks and their role as a primitive species fighting a technologically superior foe. The difference, of course, is the characters and actors of the original trilogy could carry Episode VI, they couldn't carry the abysmal story boards of the prequels.
So long as the sequels are written decently, and the acting is ok, which Ridley and Boyega seem capable of, it will be good, solid entertainment. With or without Carrie Fisher.