4Game

Heres the obvious stuff:

A new legend is coming! Revenant or Loba are the suspected two.
A map change is probably going to occur and it'll be more drastic than the Mirage Voyage. The meteors people are seeing, the "Big Bang Pizza" and area we haven't seen yet in the original trailer hint towards perhaps another reaction taking place in Worlds Edge or a volcanic eruption.
Map selection seems to be a thing. Data miners have found stuff to suggest it.

Heres the less obvious stuff:

Explosive Ticks, Reapers and Titans are definatly going to be a thing in some way. Crypto currently has voicelines for the ticks and reapers while the announcer has voicelines saying things like "warning, titanfall inbound" and such. It'd really shake things up and would make for an interesting gamemode away from non-titan gameplay.
Pathfinder or Bloodhounds lore is going to be expanded. We're getting the arcade themed event in a couple days which might give us some Pathfinder stuff but a bloodhound event to kickstart season 4 is what I'm hoping on. The location and lack of information on them alludes to something happening soon and I'm sure we'll find out in due time.
The dummy using a different variant of the L-STAR that looks and acts like a coldwar makes me feel like we're getting the coldwar this season. Or even in the event?
The sudden use of enemy AI for what looks like an event gamemode and the Easter Egg in firing range looks like PVE to me. Not entirely sure though.
Dataminers also found new hop-up attachments! Something to do with fire I think? Maybe pyromantic bullets. Idk, last time they found some weird thing in the HUD that looked like an Ammo Belt and it ended up being nothing.
Oh and theres this big box undernearth firing range when you go out of bounds. Titan hanger for testing out those big hulking beasts? Kinda feels like it to me.

To wrap up: Titans, Coldwar, new hopups, map changes, new characters, new guns, new modes, new maps, Ticks and Reapers are gonna spice the fuck outta this game and I'm so excited for the one year anniversary.

Can't really think of much else! Let me know your thoughts on new additions in the comments. Maybe let me know if I'm wrong with some of my stuff.