Well, here are my thoughts on all of this. I am a mom with two grown kids (in their 30s) and a niece and nephew that I treat as grands until I have some "real" ones of my own. My niece is 12 and my nephew is 10. My son and daughter both still love the parks though and my husband and I treat everyone to a yearly trip to WDW and an every other year trip out to DLR.
Here is the result of an informal family focus group of what my brood would love to see in the future in terms of WDW:
* Tiana's Palace Restaurant and Princess and the Frog Dark Ride: these would be adjacent to one another. My son and my niece LOVE Princess Tiana. She's by far their favorite Disney princess ever. They'd love to see the riverboat turned into a Restaurant somehow...and adjacent to that have the PatF dark ride. I'm no architect, so I'm not sure where to put this, but it would need to be somewhere in between Liberty Square and Frontierland at WDW since there is no New Orleans Square. Could they build it on Tom Sawyer Island or somewhere over there?
* Get rid of the Speedway: my son used to love riding the cars back in the 80s...but during the 90s a lot of Go-Cart places popped up where we lived and he just didn't care as much about riding the ones at Disney. I think the Speedway is ugly and out of place. What I'd LOVE to see happen is for a version of Carsland to be built at DHS and for it to include something that was not built in California: namely, an updated Speedway featuring the Cars cars for little kids to ride. This would kill two birds with one stone because the people who don't want to see this attraction go away would just have to go to DHS to ride it...and the attraction can be so much better than ever by having the Cars cars be part of it. What a fun complement to Radiator Springs Racers it would be.
* Use the Speedway land for a Maleficent roller coaster and new Tomorrowland attractions: WDW needs something for Sleeping Beauty...and wouldn't it be fun to have a coaster where you zoom around like you are riding Samson (Prince Phillip's horse) through a forest of thorns and ultimately battle the dragon and save Aurora with the help of the three fairies. The queue would be a maze of thorns with appearances by Maleficient's goblins and each of the fairies (casting gorgeous light effects in their respective colors of green, red, and blue). The show building would be hidden under a mountain topped by Maleficent's forbidden fortress...and the mountain would be shared with Tomorrowland so that from the Tomorrowland side it would look like a extraterrestrial setting.
* Tomorrowland: have a ride where guest go back in time and see life in each of the eras...from the birth of the planet, through the ancient seas, through the dinosaurs, the prehistoric mammals, and then rocket into the future to see the world one million, ten million, and one hundred million years from now. Also have a ride where guests are shrunk and explore the human body (like the Pixar movie that's coming in a few years). I'd like to see a dark ride that's an alien zoo where omnimovers take you along for a little ride like it's a zoo at the space port. A TRON coaster would be very cool too.
* Adventurer's Club Restaurant in Adventureland, built adjacent to a new E-ticket ride that would have an Egyptian theme (going through a Pharaoh's tomb or something). Characters from the Adventurer's club could be integrated into Jungle Cruise, the new E-ticket, and other places around Adventureland. Really bring the place to life with these characters...and because Disney loves synergy, maybe launch a movie franchise based on these explorers. The new Adventurer's Club restaurant would be quick service during the day and sit down at night like Be Our Guest...but would appeal to families with young boys more than BoG does.
* Frontierland: Western River Expedition with a Lone Ranger presence, as that movie is going to be a nice sized hit. Also add a Wizard of Oz dark ride where you enter through Kansas and exit into an Oz mini land that would somehow connect over into Fantasyland (not sure how, but it would be cool).
These are things my family likes to talk about. My son is an architect and loves fantasy things so most of the ideas came from him.
I really can't express enough how popular Princess Tiana is in our family though. When we were at WDW two years ago, we got to meet her AND Prince Naveen and they were just delightful. Have not seen them since, but everyone keeps talking about meeting Tiana. My niece and nephew especially can't stop talking about it.