My thought is still if it were intended to bridge over to Simba, they would've mentioned something of it... 'the first step of Disneyland forward is Avatarland' etc...
But, who knows! Could be! Being behind Hyperion and in the backlot would be tight and 'it COULD work', but that'd be it for the land, no expansion ever. Simba on the other hand would allow it to be a bit bigger (but consider, Anaheim is extremely land locked, so anything built is built with maximizing space in mind. I think regardless of where this land is, it's going to feel like a rock surrounded bowl with a pond in the middle of it.