Really? Why do you think that?
Because they never got to the cover stories, but then they teased Franky's cover story at the end. I doubt they'd tease something and then not end up getting around to it. Also, there's no reason to go into this much detail and not bother to finish it.
They need to fill extra time anyway, and these episodes are a great way to do it. I don't know when we'll get the next batch of crew episodes, though. They could very well come after Impel Down.
I trust you, but do you have a source anywhere. I do not no if I would like if they did that.
No, it's just speculation on my point. As I mentioned above, I'm not saying that the continuations are likely to come immediately, just eventually.