Another case of Savathun's cheeky antics. She was responsible for him being there at least and as some part of her plan the hive are about to rediscover some old weapons (the Choir).
Not sure exactly what consequence his death will have, but Savathun will almost certainly benefit from it somehow.
crota's faction of hive on the moon were weakened and stopped dropping seeders on earth, which made both places a lot safer for any sort of activity from humanity. those hive were scattered and without a leader til last month, as the mantle was filled by crota's daughters. between crota's death and the red war, the fallen were able to occupy more of the moon, be it through the house of exile having less pressure on them, the house of wolves turning up, or, much later, the splicers yoinking some hive for some nasty bio experiments. but the main consequence of croaty boy getting the axe (or sword in this case) was that oryx found out his deadbeat kid had been knocked senseless by the big bright orb he had been hunting ever since he made a pact with some big maggots at the bottom of fundament. then he came to our solar system, killed a few fleetsworth of awoken (and the queen), bullied some cabal, and blew a hole in saturn's rings. then he sent his taken lackies after us, which resulted in eris putting her rock on cayde's map. this key event led cayde to recognize the gravity of the situation (which was the fact that the literal king of the hive was just vibin' a few planets over) so he went behind lazy old zavagina's back and plopped us right on oryx's doorstep. we went right ahead and assassinated him, along with some more of his kids, and left the throne of the hive empty. lady savathun is now trying to waltz on over seeing as she's his sister and realistically, yeah, she could just take the throne and not many people would argue, but she's [i]really[/i] extra so she went and used oryx's pet dragon to create a time loop so she can break into the distributary (which is the awoken homeworld. it's laws of time are very different to ours, and it might (?) be a different realm altogether) so she can get REAL powerful REAL quick and ascend to the throne and also whereever else she wants without worrying about jack
tl:dr
[spoiler]we mindlessly killed a god-child and phucked up the inter-galactic monarchy[/spoiler]
We showed the Hive on the Moon that their Gods are dead and they aren't coming back.
This will likely leave a big Savathun shaped hole in their hearts that will be graciously filled.
As with Mars she sends Envoys through the Witches Ritual public event. It's only a matter of time before they are all chanting for her to Take them as well.