Mario, when was the last time fish bumped into your face when you've gone for a swim?

It's hard to think about where the Metroid franchise can/will go really. I mean Prime 2 is basically the same with a different adventure and multiplayer and Hunters is just more multiplayer. I think this is where we will really start to see the Metroid franchise at a breaking point, how fresh can they make it without ruining Metroid? They can't suddenly throw in spaceship based missions but the can't keep churning out Prime with different locations every few years either. What's even scarier is that so far we've only thought of asethetic changes, how long will these keep us interested?
I think the Metroid games need to delve into Samus as a character more, she's up there with Link in the bland character stakes. Fusion had a few brief moments where she would think aloud to us gamers, I liked that and I think they should do more characterisation in Metroid.