I think he is actually dead this time, yeah. He's faked his death too many times now, and his latest death was to in order to save and/or protect Thea. If he cheats out this death too, I feel the sentiment will be lost and people will stop caring about the character (if they haven't already).
If they bring JB back into the fold, it should naturally be the same character, but different, and from a different Earth.