Touching on a point from before, in the book they make Syrio out to be crazy good at fighting. He almost manages to dismantle the guards who come after Arya with a wooden stick until it breaks. Saying "it was a hopeless situation" seems like a cop out. He's a swordmaster, true, but I don't think it's too far fetched to assume he could disarm one of the others for their swords. (In fact, doesn't he do this by breaking one of their wrists?)
Yea, it's wishful thinking, but most of us are taught to be skeptical unless we're handed dna results proving someone died. Admittedly, GRRM could be saying, "Draw your own conclusions, because you guys know how I am...I don't care WHO dies."
I don't think Syrio is Jaqen, mainly because I think the two of them co-existing is there to show us how fucking all-encompassingly amazing swordmasters and faceless ones are.
Someone get GRRM at knifepoint and don't let him move till he finishes the series, fuck!