In "the BB universe", there is no amount of logic that would prompt Danny Reagan to move from NYC to Boston. This will backfire on CBS, I have no doubt. I loved BB, but this whole idea stinks! If they want more Blue Bloods, they should have kept Blue Bloods. The whole cast was willing to "take a hit" financially to keep it on.
deadline.com

‘Blue Bloods’ Universe Expands: CBS Orders ‘Boston Blue’ Drama Series Starring Donnie Wahlberg As Danny Reagan
CBS is expanding the Blue Bloods universe, ordering Boston Blue drama series returning Donnie Wahlberg as Danny Reagan.
