It's not Bloodborne 2, didn't have any gothic vibes. It's not any of the Souls games because that would make me violently ill and because all the Souls games have been western fantasy games and this one has a more eastern fantasy feel to it with the music and jap letters.
People are saying "Shadows Die Twice" means that it's a sequel and they're wrong. I mean, they might be right but it's not definitive. Could means it's a sequel, or maybe it's an overall theme or game mechanic, or could be nothing. My guess, it's a new Shadow Tower game.
The shadow line would sort of make sense, the trailer's theme fits the previous Shadow Tower games, especially Shadow Tower Abyss. STA also had guns in it which is something FromSoft recently tried again in Bloodborne, so they'd have those mechanics already available. All they'd have to do it make the game first person and they're good to go. A new Shadow Tower game would also appeal to Souls fans since its RPG mechanics aren't too far off from Souls games so that'd fit the criteria for the one game FromSoft was allegedly making that would appeal to Souls fans.
Honestly, I'm fine with any thing other than a new Bloodborne or Souls game. That shit got old with Dark Souls II. There's only so many fucking times a person can dodge multi hit boss combos and fish for backstabs. I know ENB pulled a rumor of a Demon's Souls remaster out of his ass a week ago but that'd be the only Souls like game I'd be fine with getting a new release.