The legendary fighting franchise is back with over-the-top action, a wild cast of combatants, rocking reactive music, and C-C-C-COMBO BREAKERS!!! Choose your ultimate combatants each with fluid animations, unique combat tactics, and enthralling special attacks.
Its the same version they launched when it released on XBone, which like you said is a demo really. It's supposed to rotate characters, but I never saw it then and wouldn't think now.
They also removed KI1, KI2, and the Killer Cuts tracks.
Edit: The Killer Cuts is bundled with The Complete Soundtrack which is sold separately instead of being included.
"Players who download the free version on its release, meanwhile, will instead have access to a single fighter, who will rotate among the cast weekly."
Don't be too excited: "a free weekly rotating fighter". KI had a demo with a single fighter before but I think it was exclusive to the Microsoft Store. The news is only about that version coming to Steam.
I think it's a good idea. Basically, it's like a free demo, but you can play as long as you like before deciding to buy. There's no MTX BS that I can tell, just an option to buy the full game to access all of the content.
Seems like a pretty good idea to me, I wish more games did something similar.