Now I know bungie said that siva will not return story wise but if you look at cayde story on how he caught the barons and when they went to spider palace they show a bunch of random aliens some were cabal, awoken, fallen,etc. one of the fallen was a splicer captain back from rise of iron now of course this didn’t mean anything but it shows at least in some point in destiny 2 there was still fallen that were corrupted by siva. now the more I think about it they could have made at least a season of that the remaining house of devils splicers could have tried to revive or make their own version of siva or head to neomuna to find that version of siva but hey I just wanted to point it out that there could have been a story.