Kalonthar
I think the Louis question is a very good one. What with word that Moranis may have passed on the project, would that mean the character is cut-out, only referenced or voiced by a sound alike. Same with Dana. Guess we'll find out.
As for Janosz, I doubt it, but I'm always hopeful for GB2 characters (after all Brian Doyle Murray is your psychiatrist in this lol) and what with the part in the article that says not only does the problem bring forth new ghosts, but also old rivals, well… we all get the idea.
What I really think would be nice is a tribute to the people who worked on the movie that have passed on. Which is why I'm really glad the original GB score is in place. Maybe an “in memory of” in the credits.
It'd certainly be appropriate in the case of Ruth Oliver, who famously played the Library Ghost who makes such a large appearance in the game.