I've been wondering this for a while now. I know that many fans consider the guy a boring character (I honestly don't understand the hate), but this guy was like the gold of the Assassins. He had the richest ancestry out of all Animus subjects. He even had the "look" of the someone special (more-so in Assassin's Creed III). I don't think this guy is replaceable, and I think, with the apparent death of him, the modern-day gameplay of future Assassin's Creed games will suck.
People hated Desmond, but this guy was about as good as it gets when your talking about a pure Assassin. He trained from a young age, had immensely rich ancestry, and just all-around had the look of a prophet or something (opinion). The only way I see him getting replaced is if the next modern-day Assassin looks as badass as Desmond did (in Assassin's Creed III) and has an ancestry so rich that they might as well be considered First Civilization. What do you guys think?