Yo!
dont be so pessimistic, my friend. These guys, these duel links devs are kinda slow fellas bcuz they are always delaying releases. But I definitely think they are going to give us Caius. Awesome card but not too dangerous for DL.
...That isn't pessimism. That's a "there is no hint that Caius is coming whatsoever". I have no opinion on Caius one way or the other. There's just no HINT of its impending arrival, let alone it being "pretty much confirmed". It'd be like me saying Ancient Gear Hydra is practically confirmed. Except I'd have more credence in that case, since we at least know an Ancient Gear Structure is coming.
Also worth noting that both of the Vassals that DO have a corresponding Monarch in Duel Links were released alongside it, making Caius even less likely.