This is definitely a BIG news. I also want to see what this additional content is. Maybe a new character/Urban Legend? That would be cool since IIRC,
Or we might get a challenge mode, or any interesting stuffs.
However, I have to bring up one interesting point.
IIRC, ZUN says that Touhou fighting games like IaMP, SWR, HM are considered to be semi-officials. Yes, he is the one making the story, dialogues, spell card names and other stuffs but Tasofro is also the one making the in-game background, animating characters' sprite and attacks so some of the in-game elements in the game cannot be used as reference (unless ZUN says so) like stages' appearance or what the skill/spell looks like.
So, this means ZUN is still circumventing the whole "bringing official Touhou game on the PS4" for now, as the fighting games are semi-official ones. I'm not saying this is bad thing. Who knows? he might be testing the water before moving on to bringing the genuine offical game on the PS4 in the future.