Iirc, Bloodborne started development one year prior to Dark Souls 2's release, so both games were developed in parallel for some time. Dark Souls 3 also started development pretty early, so I guess they're very used to developing multiple games at the same time.I'm always very curious about the period of time at Fromsoftware beginning with the release of Dark Souls in 2011 and culminating with the release of Dark Souls 3 in 2016. After a relatively quick turnaround on Dark Souls (released 17 months after Demon's Souls), there was a 2.5 period with no releases, followed by yearly releases every March for three years (DS2, BB, DS3). Of course they weren't working on DS2 for 2.5 years and then BB and DS3 for one year each… so I wonder how the development processes went for those three games. Were DS2 and Bloodborne being worked on in parallel? Perhaps the DS2 team began work on DS3 and then the Bloodborne team joined them after the game released in 2015? Do we have any concrete information about how development went during this period?
Perhaps they are in another such period of simultaneous development now, having alluded to three games in development (dark fantasy RPG, Armored Core, something new). A release in Fall 2018 would be 2.5 years after DS3, and could be the beginning of another amazing run of games from From.
It might be that we're currently in the waiting period again, much like between Dark Souls 1 and 2. Perhaps they will start to release their new games from 2018 or 2019 onwards, one year apart.