Things they have to do to make Dark Souls 3 worthwhile:
1. Varied, memorable locales: With DkS2 suffering from somewhat generic area designs and Bloodborne's limited color palette, the next game in the series needs to give us levels that are as intricate and visually enticing as the original Dark Souls. Nothing yet has topped the viciousness of Sens Fortress, the unsettling feeling of Latria or the sublime beauty of the Shrine of Storms.
Look to: Dark Souls, Demon's Souls
2. Balanced co-op: Co-op has been easy mode since Demon's Souls, with enemies failing to scale with the number of players the host summons and bosses receiving meaningless health boosts. Creative fixes like adding in black phantom enemies (Gravelord/black tendency style) or buffing bosses to NG+ levels of strength would keep the game interesting and challenging even when you choose to play with friends.
Look to: Diablo, Borderlands, any game with co-op scaling.
3. Compelling Invasions: Demon's Souls did invasions perfectly, offering unique strategies like stealth builds and weapon-breaking builds while ensuring that, at least stat-wise, fights were balanced by soul level. Dark Souls swung too far in favor of the invader, giving them passive humanity buffs for every host they defeated, and every game since has neutered low/mid level invasions. We need to return to a system where invaders can be powerful and scary (Demon's), but not so overpowered that they can be reckless when fighting multiple opponents.
Look to: Demon's Souls
4. No throwaway bosses: I can remember every boss fight from Demon's Souls and Bloodborne, but Dark Souls 2 (and the original Dark Souls, to a lesser extent) suffered from bosses that were too frequent and not memorable enough. We need truly unique, challenging encounters where any boss can feasibly be someone's favorite.
Look to: Demon's Souls, Bloodborne
5. Insane build variety: As much as I love some of the niche invasion builds in Demon's, the immense variety we saw in Dark Souls and Dark Souls 2 is without equal in the industry. Every seemingly useless weapon, ring and spell had the potential to be twisted or combined into something extraordinary. I'll never forget the first time I saw a Japanese player slaughtering entire groups of opponents with Karmic Justice, a spell that was almost universally considered garbage.
Look to: Dark Souls, Dark Souls 2
Agree? Disagree? What else do we need?