I think we won't be getting any more major characters join the crew. We will probably see a lot of characters come and go, but no one that will stay or be a major good guy. As for villians, I think that we will be introduced to more than 1 new villian. We just got Scorpious, so we won't be seeing new villians any time soon, but I have a hunch someone from the Peacekeepers may be sent out to hunt down Crais. So I think its very possible a new villian will be introduced.

As for character development, I think that Aeron and John will get much closer. After about half way through I think more stuff on the worm hole technology will be revealed. I think more on those aliens who kidnapped the crew and messed with John and gave him the key to wormhole technology but hid it from him deep in his brain will be seen again. Wow that was a long sentence. ^_^

I think we will see the homeworld of at least one of the crew members and a powerful decsision made. I don't know what but it seems like a cool idea. I also think Before the end of the series, at least one crew member will make a noble sacrifice and parish to save the rest of the crew. And this time they will die for real. But that won't be for a loooooong time.