A lot of people are heralding this as the next big chapter in JRPGs. It's gonna hit mainstream exposure. P4 got a lot of people's attention, and Atlus milked that game dry for every penny it was worth with spin offs and updates. It's only a matter of time at this point. If it's not right now, it will be with P6. Guarantee it.
I'm not sure if you understand what "mainstream" entails. That would imply complete laymans or casual gamers would recognize the name, which simply isn't happening anytime soon. Very few games are of that caliber. It may become a bigger name among hardcore gamers, sure, but mainstream is one hell of an exaggeration.
And you say "next chapter for JRPGs" as if JRPGs aren't one of the nichest genres to begin with lol. There's plenty of great and amazing JRPGs that are critically acclaimed and not mainstream or even close to it.
Like I said before, I can see this capping out anywhere from 2 to 3 (maybe 4 but I doubt it) million units, which is good for a game and genre like this, and would make it a popular series, but even that still wouldn't be "mainstream."
EDIT: Also P4 didn't sell all that well. sub 1 mill is the highest this series has ever reached before now.
And now P5 will be the highest selling, it already is in its native Japan. Give it time, it's gonna get bigger and bigger. ---
