Working title is ‘Darkest day’. Unclear whether a third prequel version of SwSh or a legends game. Being accelerated for 2023.

No gyms.
Medieval setting.
Entirely open world.
Mostly follows the same layout as Sword and Shield. Settlements will be where they were in SS original.
Crumbled tower you see in the original is a watch tower. They will be dotted across the map and host strong trainers.

Plot:
Calyrex foresees the awakening of Eternatus underground.
Lots of energy throughout the land starts to Dynamax Pokemon (they become “boss”-like opponents in the game).
Calyrex recruits you to find and prepare Zacian and Zamazenta for battle against Eternatus.
You are given a whistle by Calyrex which can summon Glastrier or Spectrier for travel (depends which you pick).
You are sent on your way to a professor exploring the region. You get to pick Snivy/Torchic/Poplio. All lines get a Gigantamax form. Loosely based on Jack and the beanstalk (Serperior - beanstalk. Blaziken - golden goose. Primarina - musical harp).
You must find lots of Meltan in one quest, to evolve them into Melmetal. They are dotted across the map. Once you evolve them, Melmetal will provide you with a sword and shield.
The sword/shield will need refining in another quest where you take them to the isle of armour for the ‘tower trainer’ (swordsmith) to upgrade them. The swordsmith will agree to upgrade them if you prove yourself worthy by evolving his Kubfu (once evolved, he’ll battle you with its polar opposite evolution in battle, and let you keep the one you trained).
Sword and Shield given to Zacian and Zamazenta. Eternatus awakes. Big battle. End.

Very plot and quest driven. Lots of other minor quests. Main quests connect all the main legendary Pokemon.