Ya. The trolls as well as Strider and Lalonde are in the Outer Ring chilling with the horrorterrors, while John and Jade are busy gatecrashing Hussie's study.
Well, last time we saw them they were heading straight toward the Troll's 4th wall (Which was not destoried, seeing as it was inside Doc's Manor, which survived.) at the speed of light. They would likely not have much time to go around and play in Hussies world. Now, if I am correct, only people with the aspects of Space and Time can travel through the Farthest Ring, which I am assuming is now the entirety of A2. Jade is the Witch of Space, so she will have no problem getting though. Then again, navigating the farthest ring is one thing, finding the Green sun is another. I don't know how they would exactly get to the Green Sun. Then again, Jade may have learned about where it is or some shit and I just missed it, I don't know.
I am absolutely sure that Jade and John aren't going to mess around in Hussie's place, because Hussie himself said that his only involvment in the story would be the "Yellow Yard", chisten so by Jade sometime ago. You may also remember that Hussie put the Fourth Walls of the Human's Universe and the Troll's Universe a
yard apart from eachother before he gave us a recap once (Or Rather, I think it was followed by a recap. But nevermind that, its irrelevant.) Hussie said that this Yellow Yard would be his only direct involvment in the story, ever. So no. Kids aren't going to met Hussie.
in Universe A2.
A2's dead. Slick shot it in the heart.
Irrelevant. The dead and rotting cropse of Universe A2 is still Universe A2. Although, I guess you could just consider that A2 was replaced by dead space from the Farthest ring, but its still irrelevant, none the less.