Level 5 hasn't announced yet if it will have DLC or not, maybe when it comes closer to launch date they will announce something, but i'm really no fan of DLC, why can't they put all the content in the game? it's not like we don't pay enough for the games already.
Probably they'll make a sequel of the Dark Cloud saga, since Rogue Galaxy didn't have a critical reception quite as good as those two games. Î really liked the game, especially for the Factory and the fact that you travelled between planets, but it felt a little lacking when compared to Dark Cloud or Dark Chronicles.
Current PC Build
CPU - i7 8700K 3.7 GHz (4.7 GHz turbo) 6 cores OC'd to 5.2 GHz with Watercooling (Hydro Series H110i) | MB - Gigabyte Z370 HD3P ATX | Gigabyte GTX 1080ti Gaming OC BLACK 11G (1657 MHz Boost Core / 11010 MHz Memory) | RAM - Corsair DIMM 32GB DDR4, 2400 MHz | PSU - Corsair CX650M (80+ Bronze) 650W | Audio - Asus Essence STX II 7.1 | Monitor - Samsung U28E590D 4K UHD, Freesync, 1 ms, 60 Hz, 28"