*Spoilers* Err.... The "metroid" was cloned. They've been extinct since before then.

They could explore into a different alien race. We don't really know much about the Metroid universe.

I thought it was self-apparent. If you want Metroid DNA, the only place left is Samus' blood.

So what if it was cloned? They stopped being extinct once they were cloned, therefore they weren't extinct in fusion.

Well there's still a hole in the plot between Corruption and Metroid II so it's possible the next game could fill in that hole. But ah that's just kind of ruining the fun. The only solution for a game after Fusion would to have some kind of new enemy show up, maybe the galaxy will finally be invaded by the Other Metroid?

Your OP actually already made me think of Alien .

Something like this will probably be the story if they continue the series after Fusion, so yeah I agree, could happen. Haven't played Other M though (or Prime) so not sure how the story would fit there. Alien's also definitely not the worst movie to take inspiration from (which Metroid as a franchise allegedly already does anyway) .

I seem to recall reading somewhere; that the Metroid effects in Samus' body eventually went away. Can't remember when Sakamoto wrote that though.

The last Metroid is in captivity. The galaxy is at peace.

He claimed that this occurred when she absorbed the SA-X at the end of the game, since it normalized her DNA again.

I'd much rather she still have some Metroid in her genome, myself. He or whoever writes story for the next Metroid could easily say "oh, well it was only mostly gone."

Yes, it should be $50.