I doubt we'll get a demo this time around, especially after what happened last time. Unless it's a kiosk demo, which is possible.
There's either the kiosk possibility, or Game Freak could build extra protection around the data so that it will be harder for data miners to hack into. I don't know if Game Freak heard about the huge data mining dump from the OR/AS demo, but if they did hear about the leak spreading over the internet they would likely try and counteract as to avoid another leak like it.
And back to the 4chan thread Pinkie leaked, if the other island guardians alongside Tapu Koko are Grass, Fire and Ice that will likely mean the four islands are themed around green, red, blue and yellow like previously speculated. It also mentions Tapu Koko is a legendary which I expected from the moment it was revealed due to its bio. I also find it hard to believe Marshadow could possibly be the first-ever Poison-type legendary, something we had to wait seven generations for.
The question is, does the possible 109 new Pokemon total count Alola Forms? Because Game Freak often counted Mega Evolutions as new Pokemon, but we also have to consider that Megas (and likely Alola Forms as well) take up the same Dex slot as their normal counterparts.
The thread also says Pikipek is the line that comes after Popplio's in Pokedex order which reminds me of the Starly line immediately following Piplup in Pokedex order back in 4th Gen. Based on what is mentioned this is likely what the National Dex order for the starters + Route 1 new Pokemon is:
722 - Rowlet
723 - Rowlet middle stage
724 - Rowlet final stage (Robingroot)
725 - Litten
726 - Litten middle stage
727 - Litten final stage (Panthster)
728 - Popplio
729 - Popplio middle stage
730 - Popplio final stage (Entermaid)
731 - Pikipek
732 - Pikipek middle stage
733 - Pikipek final stage
734 - Yungoos
735 - Gumshoos
736 - Grubbin
737 - Charjabug
738 - Vikavolt
(Robingroot, Panthster and Entermaid were the names mentioned in a translated version of the Chinese leak)
Yungoos line I'm expecting to follow Pikipek, while Grubbin line comes after Yungoos, like how 4th Gen's new Pokemon had Starly coming right after the starters, then Bidoof and then Kricketot.