desmond isn't dead!!,if you notice in the ending video,he puts his right hand on the pedestal nd that ****s him up,right?this means juno probably meant to use up his body or something,but if you guys remember the ending of revelations,you would remember that in the end when animus schedules subject 16 and desmond
for deletion,subject 16 clings to desmond's body and desmond glows blue(particularly his right arm) and 16 tells him that he is 'saving him',then desmond comes out of the animus and his right arm glows blue for a while.what had happened was that clay(subject 16) had stored himself in his right arm and so when desmond touches that pedestal,clay probably saves him somehow.there are explanations for adam and eve too,the people behind AC are very smart to say the least.now that juno is the big baddie,the assassins have to stop her,right?well in the time of the first civilisation,there was a human revolution,and somehow they defeated these smug god-bastards,so what desmond(who is probably adam's descendant) will do is go back to the time of the first civ. through the animus.but there is also the matter of eve.adam and eve probably lead this revolution(the eve part can be confirmed through ac:liberation's ending),so desmond will have to find eve's descendant,nd they both will find out how to defeat juno.(so this is how co-op is possible,something ubi have been talking about).also all this is also hinted by brotherhoods ending,where clay says to desmond-to find eve,and says d key is her dna.