I've had an opinion brewing back in forth in my mind for several years now. I feel that King's Quest should be something much larger than it is and ever was--That a King's Quest game shouldn't be a series limited to the Royal Family of Daventry, or even to Daventry itself. It shouldn't be a series limited to the Adventure Genre, either.
What do I mean by this? Well, I look at worlds like those of Dungeons & Dragons (The Forgotten Realms in particular), or the massive world of JRR Tolkien and I see realms full of almost unlimited potential for stories, intriguing characters and exciting adventures. No single kind of story dominates the worlds of Tolkien or the world of D&D--Middle Earth is a place where ANYTHING can happen; So is the world of Faerun in Dungeons & Dragons' Forgotten Realms setting.
There are so many stories spanning so many epochs, genres, varying in tone from dark and dreary, to light and happy; From creepy dungeon crawls, to grand epic adventures.
Consider the vast variety of material in The Silmarillion alone, to the sweet, simple Hobbit, to the deep, methaphorical Lord of the Rings. Consider the many realms in Middle Earth, the hundreds of stories, the multitude of characters and legends.
Or consider the Forgotten Realms. You have a planet called Toril, a continent called Faerun and several other large continents; Within those continents, dozens and dozens of countries; Within those countries, the detail contained in the source guides depicts hundreds of cities, towns, hamlets and the like, thus giving room for endless amounts of stories.
Why shouldn't KQ be this way? Why should King's Quest be limited to just four characters in a very specific timeline?
I think the KQ Universe should take on a life of it's own, in the same way that the Forgotten Realms, or Middle Earth did. We should get to more about the lands of the world of Daventry and be able to experience adventures through the eyes of royals of the other lands.
KQ, IMO, should not just be bound to the adventure genre. It can be an adventure game, sure, but it shouldn't be trapped in that one box. There's so much potential in the world Roberta created that there should be room for everything. Why should KQ play by a very narrow and specific set of rules?
This was Roberta's own framework for what made a King's Quest game:
"The components that make a King's Quest are (in my mind, anyway and since I am the creator of the series, I guess that holds some weight):
1) A land, or lands, of high fantasy;
2) Fantasy creatures from myth, legends, and/or fairytales both good and bad
3 Situations to be found in those same types of stories
4) A "quest" type story; a calamity in the land with one "hero" to "save the kingdom"
5) A story of the "good" hero against the "evil" bad guy
6) A story that everyone can relate to, i.e., a "reason" for having the hero go out and risk his or her life for "saving the kingdom"
7) Interesting worlds to explore

High interactivity
9) Interesting characters
10) Great animation
11) Great visuals and music.
Within that general framework, I feel that I can have some "leeway" to accomplish those tasks."
As you can see, Roberta's own framework was not that tightly bound--rather loose really, allowing for a whole variety of Quests.
I don't see why, for example, we can't have a KQ prequel showcasing the adventures of John the Wanderer, or maybe a side-story about King Edward's adventures, or the adventures of some King from another land, or a story about King Graham's adventures when he was just Sir Graham.
I think the KQ universe should be all encompassing, like the universes of Middle Earth or the Forgotten Realms. If someone wants to design a KQ6 style KQ, go ahead; If someone wants to design a light hearted, Disney-esque KQ ala KQ7; the door is open; If someone wants to make Mask of Eternity II; Excellent.
KQ shouldn't just be limited to a very strict set of rules. It limits the series and curbs it's potential.