My oh my. You might be on to something there. You could also tie up some other stuff. For instance, Rory's paranoia that Amy wants the Doctor and not him. In a different dimension, Amy actually gets with the Doctor and has a baby. That could make Riversong the Doctors daughter, not wife...(are they ever shown to be romantically inclined, or is it just implied they have a close relationship?) Which is why she knows everything about him including his name. Riversong has said when she first met the Doctor, he knew everything about her, and it is implied she is as smart as a Time Lord. What if thats because she was his child, and 'he knew her' means he could relate to her being a young time lord growing up. Ie, the timelord girl we see in the first episode. Eventually in this series, they find that girl and the Doctor 'adopts' her. Also, the timing when Riversong dies in the library is when the Doctor doesn't know her at all. What if that was a deliberately ploy by the Doctor because he couldn't bare to knowingly watch his daughter die, so instead witnesses the death of somebody he has barely met.
Dun dun daaaaaaa.
Ie he has a baby with (alternative dimension) amy, he then travels all time and space with her as she grows up, but cannot cope with watching her die so instead she dies before he has ever met her. He then comes to terms with her death over the course of her life
Series Super Title : The Doctors Lament
Sounds VERY moffat to me.