However, keep in mind that they did say Artz (the guy who got blown up in the last episode) was going to be a major new character in series two. So they are not to be completely trusted
Yes, but he could still be a major character in some of the flashbacks. He may have had minor interactions with the main characters that we don't know about yet, and he may have had major interactions with characters that are going to be important in the new season.
Or it could be something more devious, like maybe it was an imposter that got blown-up, and the real guy is about to stumble out of the jungle declaring that he's been kept prisoner by the Others; or an imposter could stumble out of the jungle and pretend to be the original, or--
The possibilities are endless with a show like this one, and I wouldn't count anyone out for the new season, no matter how dead.