The demo has a different and unrelated story to the main one.

The best thing that can happen

>>29170448
ORAS demo also had aa separate story

Yes, no shit. No one is actually expecting that we'll be able to pull models and textures from unused pokemon and routes, the point is that the metadata like names, dex entries and moves will still be in, and that's kinda all that matters at this point.

>>29170448
you don't understand how this works, do you?
ORAS also had an original story, and it cut out all the models and music irrelevant.
The issue is its hard to alter metadata without introducing new bugs, and the metadata is where we got all the information from.

And no, it won't be "coded completely separate from the game", that causes so many issues that it'd be the most incompetent thing Gamefreak has ever done, all just to prevent us from knowing a few things a single month early.

>>29170448
Datamining will not fail.

Demos are made from the same skeleton as the main game. Models and such will be scrubbed out, but most likely pointers for such will remain to prevent the code from craping itself and crashing all over

Even if the pokédex preview images are removed (they weren't in the ORAS demo, that's how we found out about Hoopa-Unbound), at least the dex constitution is likely to be revealed