This may seem off topic because I just got into the conversation, but I kind of want to feel included...I'm always ready for a Devil May Cry conversation relating to Vergil.
This is my opinion. Vergil isn't necessarily dead. This is what I thought had happened. When Vergil made an attempt to break free of Mundus's spell, it almost worked, because his face showed up. Dante defeats him. Keyword: defeats, not kills. Quote from Mundus: "Trish, Vergil has been defeated," And he disappears with blue flames surrounding his body. The Nelo Anelo suit must have broke off, because an amulet came falling down afterwords. Oh, and this explains why the Yamato sword was broken in Devil May Cry 4. That sword that Nelo Angelo was carrying around was actually the corrupted form of the sword Yamato (in case you didn't know). When Mundus's spell no longer had an effect on him, the sword went back into it's original form. Vergil isn't dead, and he may make an appearance in DMC5. Now, do you really think holding your head, floating into the air, and disappearing, leaving flames in your wake, is a way of dying? Tch, hell no it isn't! If Capcom wanted to kill him off, they would've gave Vergil a much cooler death, mind you. He's a son of Sparda. It'd be freaking silly to leave him out. And here's a little side note I'd like to add on him and DMC4...He definitely has a connection with Nero. Why? Well, look at his devil trigger for instance. Doesn't that remind you of Vergil's devil trigger in DMC3? Hence, the sword is attached to his wrist. Either that's Vergil's spirit, or, as much as some of you guys hate to hear it, that kid is his son. Nero really wanted his 'daddy's' sword a lot in that game...one more thing, remember in DMC4, when Sanctus said to Nero, "Still, I must salute a man who carries the blood of Sparda. While not in Dante's league, you still presented a harder fight than I had anticipated"? Ah ha! That proves it! ^_^ Too bad Nero will never be as strong as Dante or Vergil.
(Longest comment in history? XD)