User blog comment:Lancer1289/BioWare gets on the Multiplayer bandwagon/@comment-125.209.147.88-20111017101458/@comment-10385287-20111017112537

It will actually have some impact on the single player campaign, but Bioware have stated that you will still be able to get the best possible endings in single player without whatever benefits the multiplayer will offer. Basically, the multiplayer offers players an "alternate" way to help achieve the in-game goals, or something along those lines.