i wouldnt mind a proper sequel to dark souls. i mean DS 2 is something of its own kind and ds3 is more fan service than anything.
They should do something modern. Dark horror modern stuff. Maybe Nocturne adjacent or something.
Edit: complementing the idea... what if they buildup on Sekiro's combat system, opening it up for a myriad styles and weapons? Keep posture in place, bring back stamina, replace the super dodge for something more grounded, etc.
Make it a Nocturne/Fist of North Star-ish setting where firearms are rare and society devolved into melee weapons and voila.