Atlus' collaboration strategy is a neat one. Despite only having around 121 employees, their internal development output seems remarkable because of the cost effective way in which they handle things, one of them being how they seem to leave the fundamental efforts for their spin-offs to the respective developers who have the required expertise (and there's also SMTxFE). It strengthens the Persona brand, while growing Atlus' library and—in this case—potentially leaving them room to focus on their bigger titles, like Persona 5.
It's something I can see them continuing to do in the future. Heh, kinda like a Space Dandy type of deal where renowned Japanese developers have their unique twists and takes on Persona.