I predict a lot of Godzilla fans being super disappointed come 2018 when Legendary's Mothra isn't a magical creature who consciously lives the role of a goddess to a population of islanders, among them twelve-inch twin fairies who always speak in unison and can communicate with the monster. It might be a good idea to check those expectations.
I get where GoDziLLaX was coming from in his initial post. There are different approaches to monster movies and G14 definitely goes full sci-fi rather than fantasy, with pseudo-scientific explanations for the existence and biology of giant, fictitious animals. It's the de facto "realistic" approach to the genre, relatively speaking. Seeing the Shobijin translate monster talk in G14 would have felt as out of place as seeing it in G54.
Of course there's nothing wrong with sequels taking a drastically different approach from their predecessors, which is how G54 led to
Ghidorah the Three-Headed Monster in the first place. The possibility that Edwards, Tull, et al. will end up making
Godzilla 2 more of a fantasy movie is certainly there but I'm not betting on it.
As fans, it's natural to hear the announcement of a classic monster and mentally assume that a whole lot of historical baggage will come with it based on individual ideas of which previous film appearances defined that character. It's easy to forget that turning Mothra into just another Earth monster has been done before in
Destroy All Monsters, by Ishiro Honda no less. That film completely avoided acknowledging the concepts of the Shobijin or Mothra's deity status on Infant Island and it's the very same movie that Edwards as inspiration for where he might go with
Godzilla 2.
I don't think King Ghidorah having three heads or originating from outer space would clash with the sci-fi world of Legendary's Godzilla at all.
Notice how nobody is worried about Rodan?