I don't see how they can do anything other than cosmetics and maybe refresh a weapon pool as craftable since they just found out about this last month.
Here's my guesses for what we might get:
A new Moments of Triumph armor set tied to a set of objectives with a corresponding title.
VoG or Garden gets craftable weapons+updated perks.
I guess they waited until they had a better idea of what they could offer over the longer season and the day before the next dlc is about as long as you could wait really.
Kind of shocked they announced it today. Really thought they'd hold off and announce the delay in like January. Simply for good will from the seaaon (potential) and more sales/preorders due to the December holidays.
Some of this stuff should be pretty nice to have. We can guess as to what Moments of Triumph will look like, but hey more shaders/sparrows/ships tied into triumphs from that should be nice. The Into the Light thing could be cool.
Disappointed in the delay. Gonna be a loooong season.
Really hoping they make it worth the wait, though. I don't have a ton of faith in Bungie after this last year's worth of pretty consistent bad news from them (awful Lightfall launch, problematic storytelling that embedded campaign-related story into the seasonal content, layoffs, etc), but I'm still hopeful that they can correct course and deliver on their promises.