I don't think they'd drop portraits just for the sake of dropping them-- I mean, the art will still exist to get shoved into a menu somewhere (think the S.Link menus in P3 and P4). They'll always go for what looks best.
The only scenario in which I'd see them going away (which isn't to say either way what the likelihood is because of how little we really know about the game) is if the in-game render looks better without portraits cluttering it up. So at that point there's no reason not to be excited. Either it will look just like one of my Japanese animes or it will have portraits styled after my Japanese animes laid atop the image like I'm used to!
The only scenario in which I'd see them going away (which isn't to say either way what the likelihood is because of how little we really know about the game) is if the in-game render looks better without portraits cluttering it up. So at that point there's no reason not to be excited. Either it will look just like one of my Japanese animes or it will have portraits styled after my Japanese animes laid atop the image like I'm used to!