Anything is possible with DLC... especially over a 10 year time frame!
But I wouldn't hold your breath for either of these things in the first year.
Adding playable Elites is a huge undertaking (models, animations, sounds etc) - and is probably not worth it for a small percentage of (vocal) enthusiasts. I think the best chance is when they (hopefully) add the Arbiter back into the campaign - and then his assets can be easily transferred to multiplayer.
And dual wielding is a broken mechanic. Previous efforts have caused big problems for the weapon sandbox. I can see why they don't want to touch it with a barge pole. Maybe, a few years down the track, when the Infinite sandboxes are humming... but I doubt it.