either im really awesome, or i really really suck...
i managed to kill off everyone that i didnt really care about in the last mission...miranda and jacob (jacob is fine but hes cerberus and all >.>), samara, jack and legion (legion was ok too but only cause he told you more about the geth, and he did that already)
so yeah... you are all talking about how easy it is to preserve m all but i couldnt really help it at all...all the deaths depend on what you do before the mission, ship upgrades and side quests etc.i did most of the loyalty side quests and got all the ship upgrades.
really though, how the hell are you going to have any chance in the 3rd game, its just crazy imposible...probably some lame thing like "if you upload a virus thingy then they will all explod! must escape out here fastly!" and you have to get a completely new team in 3 as well...or they have to make the whole story with your origonal team, and again with new characters that replace the dead ones...