I really don't see them changing characters like that...
In a show like this, people associate with the characters quite a bit. Not to mention the ending of episode 18 was quite the ending that I think people would really like to see what happens.
*possible spoilers... will be vague*
Although, I will try to be vague in my discussion of the episode so people who actually wait ( HOW CAN YOU WAIT!? ) won't have it spoiled. Essentially, the future as seen in the episodes can still occur even if what happens at the end still goes on. In my opinion, it'd actually make the explosion more likely as you'd be going from relatively trained to untrained.