Yeah, but I guess they could put Arem in the game without making him so proeminent. Also, I like the way Dawn of Ys fits in more tightly with the story of I-II. Anyway, I guess the game design will be quite different from Mask of the Sun.
I've also heard that rumour about Ys V but I don't know, it sure feels like a Falcom game (the world and character designs), and the only company that's mentioned in the opening and ending is Falcom. While it's true most Ys games we've played were not made by Falcom, they are pretty faithful to the PC88 originals, even if they added some fancy cutscenes (PC Engine versions, specially). Ys IV was different in that there was never an original made by Falcom, so the world design and character art which are always strong points in Ys games were made mainly by Tokinhouse and Hudson. The opening in Mask of the Sun has pretty good graphics but in game its not that good, and I think the world map is very badly designed, too much of a straight line (if you wanna go back to the first town you have to pass through all the places you have already been to). Dawn of Ys has awesome art in the cutscenes and ingame is as good as I-II, but I don't like much their dungeon design, I think it's too much of a labirinth compared to the other games and sometimes you go through dungeons where all the rooms look the same. That's basically why I think the game would be much better if Falcom had made it in the first place.