They could probably rebalance the difficulty level. I want to say SMTIV manages it, but the difficulty in that game ends up dropping pretty soon. I just don't really like how the MC is this unique snow flake. I guess I just don't enjoy self-inserts that much.
They would have to get rid of All Out Attacks to start. I mean, they could just buff enemy HP, but does anyone really want to sit through an AoA at the end of every character's turn? They would have to get rid of being able to knock down an enemy to skip their turn as well.
The Press Turn system has some other things to keep it somewhat balanced like switching demons taking a turn and removing a potential turn along with the MC having an unchangeable skillset in the middle of battle, though honestly I think it's even easier to break in favor of the player than the current One More system. Even Nocturne becomes a walk in the park once the player realizes they have all the time in the world to stack buffs/debuffs that have no turn limit.
I wouldn't mind seeing seeing everyone being able to use multiple personas, but it would need to be in a different battle system because I can't see it working with the One More system without taking out a lot of the fun stuff. I thought the EO team handled it wonderfully in Persona Q. However I also enjoy the current system enough that I'll be happy if they just continue to build off of it.
JLPT1. Unless you're native or near-native, expect it to be difficult.
I'm going to struggle my ass off but I'm still getting it day one
I am nowhere near ready, but I really want this game so I'm preparing for the struggle. I'm going to be in over my head and I'm gonna love it!
Assuming I have the money to import it...
I played through Persona 4 when I was at around N3 level. I didn't have trouble navigating battles or understanding what skills did and could get the gist of the plot and most of the dialogue in the everyday life segments. Serious scenes like news reports or the more complicated social link problems or the villain explaining his motives and why humanity deserves to decay etc. was difficult for me to understand perfectly though.
That's about what I was expecting.