On that note, what style of multi-player would you all like to see?
If it were up to me, it would be co-op squad-based missions. Regardless of how ME2 ended (assuming Shep surviving is canonical) the ME universe is gearing up for a war. So it would fit to have the game place you in the shoes of a recruit and get sent on whatever objective based missions with your friends/fellow recruits in a side-story that is parallel, but not necessarily directly related to Shep's story.
"Women are like sunsets… they’re beautiful, but there will be a different one tomorrow." - Gilder