Raptor owners are not concerned about gas mileage. Ford didn't expect to sell as many as they did with gas prices where they are. After that, I think they should just get the 6.2L to 500hp and with the new aluminum frame it should shed some weight so that would be nice.
More travel would be awesome, but doub't they'll do that though as the mass doesn't use it for what it is intended for..
The raptor's current road manners which are great would be compromised if they changed from a mid-travel to a long travel suspension setup I think. I am betting that's what will prevent much more travel from being added from the factory.