The Clone Wars ran for five seasons and it wasn't eight-year olds who bought up all the DVD's and Blu-ray's.
Thing is, if you don't figure out a way to draw those kids in, Trek will wither and die as those of us who are fans grow old and pass away. Making a super-serious series solely targeted at adults is the surest way of killing Trek for good.
You sure just said the name that put me most worried. It is true, I have watched Clone Wars until somewhere middle of Season 4 than gave up. I just couldn't take it anymore. True, there were some excellent episodes, but half or even more per season were mostly episodes about R2D2, some clones fooling around, Amidalas adventures with ultra damned down stories that were a pain to watch. And this is what I'm fearing about from Star Trek being a cartoon.
And I'm not wanting a super serious approach at all, I just don't want a dumbed down cartoon. You think it's okay to do a kids cartoon ignoring the millions of grown up fans? They should do a live action TV series and a marketing for the kids too. TNG wasn't dumbed down, it was a good TV show (20 years after TOS so fans where aging too than), still it had been a great success and appealed to kids without being animation. You just have to find a way to make kids aver too, the rest will come (I know it came too me, I become a TNG and Star Trek fan when I was 10)