I think one of the most interesting things about Lucas' Universe is there IS a great deal of room for adversity. If you've got thousands of planets with life there is the possibility that it will run the gamut between cute and cuddly (Ewoks) to big and nasty and slimy (Jabba the Hut) to big, bad-ass warrior tribes (Wookies).
The biggest problem with the latter movies is it appears Lucas tried to focus too much on the cute/cuddly/silly side (everything from the young Anakin to Jar Jar) and left those of us "adults" with the feeling we were watching a "Saturday morning cartoon" version of Star Wars.
If you've got an "Ultimate Evil" that is trying to take over the Universe and you DO have a large diversity of life, it's inevitable that you will eventually have a "Storm Troopers VS Ewoks" chapter. The trick is to know when and where to tell that chapter of the story. That is the sort of story that WOULD play well on Saturday morning and it works out for everybody (the story is told, the kids get their content and Disney gets to sell lots of Ewok and Storm Trooper paraphernalia).
However, if the movie writers DO decide that "Ewoks VS Storm Troopers" is an important part of the storyline for one of the new movies, I'm just hoping they keep it in context and don't try overuse those cute and cuddly characters to the detriment of the entire movie.
It's really not that difficult... Disney has a gold mine with this if they just follow the formula of "A New Hope" and "Empire Strikes Back" for the movies and will be content to leave the lovable, kiddie stories for Saturday morning.
So, here is your chance Disney to give those of use old enough to have watched the original movies in a theater hope for another, "A New Hope".
Just don't forget this: A big part of the reason so many of us loved the Han Solo character is BECAUSE he shot first