Hopefully that'll be the case, but I'm thinking about the director and the studio in particular putting pressure on. I'm also worried about Kasdan himself, his last film wasn't very well received (Darling Companion) and he's actually been quite good with that genre in the past (French Kiss was a good film for instance) so I'm wondering if he's still got it or not. If he hasn't, he might find himself deferring more to Abrams (who as I understand it is also one of the co-writers), who has been seen to use Monomyth, and Disney pretty much helped to make that an industry standard to begin with; they've been using it for decades, so you can bet money that anyone else they bring in for creative, any of their own people, will be at the very least aware of it, if not drilled on it.
One thing to note though is that there's a difference between the original Monomyth that was written by Joseph Campbell and the modern one, which was adapted for commercial use. Because the commercial one has had a lot of success in the past, and because Star Wars cost a lot to acquire and is guaranteed to draw an audience, they'll be wanting to hit a home run on it. That means repeat-viewings, toys/merch, DVDs (or, y'know, digital sales). And the trend in recent years for big budget films aimed at being blockbusters is to play it safe (which means formula).
Another worry I've got is that they picked up Kasdan and others more for marketing purposes. If you look at the prequels from a business perspective, they'll be looking at ways to repair the damage. Star Wars is a guaranteed hot property, but they'll be wanting to maximise the revenue they get and that means repairing trust in the franchise. And a way of doing that is picking up people involved with the original trilogy, as if to say this is going to be a lot more like those films; it's trying to give this new trilogy an early sense of success through association.
But I guess we'll see what happens. Not personally looking forward to seeing old Harrison Ford though; nowadays he seems to suck all the energy out of every scene he's in. It's painful to see him in films nowadays and then thinking back to something like The Fugitive.