Oh, cheer up paul, just because they can't sense Ginjou's energy, doesn't really mean that he is dead (at least his soul), especially when the creator of an untraceable gigai appeared at the scene and all the other people who cared for him (and were at the scene) were practically unconscious. It should be mentioned that if he was in his real body - thus a living human - then after death, his soul might have just came out of it and was put in one of Urahara's gigai to make everyone think that he is dead (when was the last time that someone died from a cut like that in Bleach ?).
Perhaps this way, he still would release all of the Fullbringers of their need to repay him, or something , yet it still could be said that his life full of vengeance, meant for only vengeance, was over . This would allow for his full story (just a flashback ) to be revealed, by which we would enter in to the Ishin's past. Let's not forget that supposedly, there is still one chapter left, to close this arc - seeing as this is a Lost Agent arc, the arc should end by finding and dealing with him .