well, I already know what would come out in the next DLC

(no, I didn't hack the BW servers and no, I am not an Employee)
We will get new weapons
Basically all the weapons from SP that are not available in multiplayer, mostly DLC weapons:
ADAS Anti synthetic rifle (assault rifle)
Blood pack punisher (smg)
Blood pack executioner
Venom (shotgun, shoots explosive rounds similar to the Scorpion heavy pistol)
Chakram launcher (assault rifle, people got that one for doing the "kingdoms of amalur demo), will be available for everyone in SP when ME3: Omega comes out
Additionally there MAY be some new mods for the weapons, like for example a mod that improves the rate of fire (though it will most likely use the spot of the piercing mod or clip size upgrade so you can't put them into the same gun (to keep them balanced)
Furthermore, there COULD be a clip size upgrade for sniper rifles (though if the sniper rifle needs to reload after each shot like the Widow, then the clip size won't change
More ammo types... nope, there are too many already, the game did fine with the ones that we had pre-retaliation
Gear equipment... maybe clip size enchancers/moving speed increasers (if there are not such here already), rate of fire improvers
new characters? Maybe, but only expect one or two for each class
new maps? all the DLC maps get a hazard, but there won't be all new maps (because there are too more than enough maps here already)
New enemies?
haha, quite possible, Cerberus could recieve the mech seen in the omega DLC (you could see it in the demo of that DLC, videos are on youtube), the finished mechs on the ground become mines if stepped on by accident
The geth could get an actual close combat class that CAN kill you in one go (like the Cerberus phantom), that way the geth will (finally) become challenging
The Reapers... who knows, some support unit that gives out barriers doesn't sound bad
Collectors... they need a proper "hunting" close quarters unit, piece something together that would do fine
Well, additionally we could get some better options to cutomize your characters appearance (more different patterns would be fine)
AAANNNNDDD::
PVP... finally, it WILL come out
haha, just joking, you can hope for that in the next mass effect game (Mass effect 4, the one still in EARLY development, I kinda hope your ship will be BIGGER than ne Normandy SR2)
And maybe the next MP DLC will feature more Prothean weapons (come on, the protheans didn't only shoot with an oversized laser pointer)