Is it me or does Buttercup's right hand look... deformed?
Either it's just a fudgeup or Bleedz took a weird time to adopt the Powerpuff original style. Which is actually less likely since Blossoms hand seems normal.
It's like cankles for the arms!
But yeah, no- here's what could happen.
We assume Blossom won't get hit because she already had a near-death incident. But that doesn't completely debunk it. It could happen purely because everyone thinks it couldn't.
Buttercup is hit, though I don't think it would result in her death. She has too much character development potential in the future... Unless this is what would trigger it.
Sam manages to hit herself instead. Which would provide a healthy amount of irony, considering she's so hostile. She would end up hurting herself.
I don't think it could hit Bell or Gir. They seem to be outside of the chaos. Unless the sword comes flying out of the smoke into them. It wouldn't make much sense though. We kindof want/need the to die. For it to just happen out of fluke is silly. The only reason it would happen is because it would be the least expected.
They hit the bomb- although I'm not sure if it's near them at all. This would be the before mentioned 'mistake' which seems most likely. At least in getting to the point of how it went off. And such.....
Oh, or- maybe by some plot twist it DOES hit GIR. And HE'S the one who explodes..... Hmmmmm......
Anyway. Those are my ideas.....