As for the original question which characters are to return:
From what Aria (Ducky) told us they are looking for a voice for Chomper, so I think we can take it for granted that he will be there. I like the idea of another story with Chomper, but I hope that they care to give a good explanation on how he got of the island. I really dislike the idea of any plots that contradict earlier stories.
For that same reason I wouldn't like to see Bron again. There were so many points about his story that didn't fit into the world of LBT at all that I would prefer they had never ever come up with him.
I consider a return of Ali not unlikely and I hope that she does return. They can easily make up another good story with her.
The same goes for Pterano he and his either earning his recognition or else proving himself to be a real villain could make for a good story. I hope they think the same way.
Mo is a character whom I don't believe to see again, though I would certainly not object his return. Both Mo or Pterano could possibly return in a story along with Chomper, as both of them have access to the island limited "access" in Mo's case.
As for Mr. Thicknose, I have certain doubts about his possibilities to return in a major role. However, with him being the oldest known resident of the Great Valley he may well appear in a minor role telling for example about events of importance that happened long ago.
Speaking of long ago, Mr. Thicknoses reappearance might be combined with a return of Doc. Mr Thicknose may remember Doc's earlier visit to the Great Valley and perhaps he knows more about Doc in general. Perhaps Doc is somewhat similar to Thicknose (who was believed to be very experienced in the Mysterious Beyond) with the difference that Doc tells no fibs while others exaggerate and mystify deeds of this taciturn longneck. I am not sure however if the legend of the lone dinosaur should be demystified or confirmed.
Hyp, Not, and Mutt could well return in my opinion. I don't think that they would ever totally abandon their habbit of big talk and bullyish behaviour. I think that they could well show up again.
Dinah and Dana could possibly return. The same goes for Tria. It would be strange if she was just gone after the events of LBT 11. As for Dinah and Dana, there ought to be an explanation for their relationship with Cera and her father. I think that he adopted them for it would make little sense if Cera had sisters in the Great Valley who are hiding from us all the time
It is not only "friendly" characters who might make a return. What about the villains?
Ozzy and Strut from LBT 2 could well show up again (why not combined in a story with Chomper against whom they may have a particular anger because of his parents expelling them from the Great Valley where (I suppose) they could never return.
Ichty and Dill could perhaps return. I don't really "like" them, perhaps because I really found their song very silly, but the general idea of two villains who detest, but have to depend on each other is not a bad one.
Rinkus and Sierra might return along with Pterano, but this time perhaps as his enemies (seeking revenge for what happened in LBT 7).
