SDNL will hopefully give us a more balanced, consistent PvP FPS experience. I think this would be nice for both large group plays and 1v1s. Right now the most traditional version of that experience is laser tag, but with forced teams and inconsistent players the teams get lopsided easily.
Also with the weapon prediction proving successful in Virus and Laser tag, the backbone seems to already be in place for SDNL. Accelerate will be amazing but probably one of the more challenging and long developments of the game modes, as we really don't have anything like vehicles yet. Seems like there is too much in the pipeline currently for the dev team to tackle an obstacle that big, but this is all conjecture on my part.