Well, if the book was written this year, say as part of a new series, and GRRM had a history of doing that kind of stuff (which I don't think he does btw) I'd say it's possible, but he wrote that in what when the internet didn't have the pervasive influence that it does today. I beleive we didn't see a body is because Syrio wasn't killed.
There are various thrweads on this forum which talk about Syrio and Jaqan being one and the same, about how Bronn beat Ser Egan relates to Syrio and Ser Trant, how Syrio had already disptached the 4 morons with Trant and could have grabbed one of their weapons, how Syrio happens to appear in the book around the same time that Jaqan might have, etc. etc. It makes for good crackpot reading.