Honestly, I'll take whatever they put out.
I have to ask though, how would demon negotiation work (at least in the framework of P3/P4)?
The shadows you fight aren't the same as the personas you can summon.
It works out in the other Megaten series because the demons you can fight and control are one and the same.
To those people that have issues with being able to pursue multiple social links at once: in the beginning of the game, the MC is asked to "wear many masks", which is what the power of Persona represents. If the main character can change persona at will, then what stops him from being able to act differently towards the people in the S. links? And further, does he even act differently? The MCs in 3/4 are silent protagonists, so you can only infer what the character is actually thinking (or since it's an RPG, maybe your thoughts are the character's thoughts).