I was referring mainly to the video that you posted, NW15. I believe the series could very well (and frankly, should) take that kind of plot twist. Again, the ending cutscenes for AC:B are not fresh in my mind, so I'd have to rewatch them to really formulate my thoughts. But based on memory alone, I'm positive that a pregnant woman is not reliving Desmond's life. They state very clearly in the clip you linked that they were referring to Subject 15, two test subjects before Desmond (Subject 17). It is possible that desmond is a memory within a memory, and it's also possible that it's not. We'll have to wait until they announce the next major AC game, which should happen by E3 in June at the latest. Considering it's been confirmed that another major AC game would be coming in 2011, the latest they could possibly announce said game would be E3 in june. Ideally though, they'd want to do it before that. Mayhaps GDC 2011 is a good place?