Ehh...that feels like a real stretch in most places.
The only thing that does stand out to me amongst those is Sylvanas' powers. You would think they'd take on the same greenish hue the death magic does but it doesn't. That is curious.
The rest though...I don't really take those as hints. Bolvar's coloration has been like that since he got bathed in flames, it would have been odd for him to not still be red/orange. The hammer thing doesn't strike me as anything more either. And the sky coloration is really just two common contrasting colors (orange/teal, but more muted), that color combo shows up in so many places.
Don't forget that Blizzard sometimes puts in things that end up going nowhere. There's a worgen NPC stealthed in the Alliance's shrine that talks about how dangerous the Ethereals are, yet nothing has come of it (yet, anyway). And at the tail end of MoP, on the Timeless isle, Blizzard introduced three Timewalker NPCs who are clearly each a spec of a Timewalker class (they talk about their duties and one is obviously a tank, one a healer, and one DPS) and again, no Timewalker class ever manifested.
They do put plot hooks out there from time to time but this feels a stretch to me.