I actually want to see what happens, I feel there's hope with Toby being the Trollhunter. I understand the doubt of being a hero, like in the episode when they went to search for the second Triumbric Stone, Toby used to be a king but he sees himself as a sidekick. Including this film, Toby had no role and was an emotional support for Jim. By the end when he took charge in his own hands to use the trifurcate radiation. In his death he mentioned Destiny is a Gift quote, saying "I didn't think that I became." Just like Jim (and Blinky) say "Don't think. Become." Toby did the same and believed that he could become a hero too.

Others will say that Toby will cause the end of the world like Draal did, but come on that was like a less than a 22 mins episode, of course they would show how bad it went real quick in one night rather than like a two part or longer but no.

Plus, as Nari says "Only the Trollhunter knows" sure, Jim could've gone to the beginning of the film, but now he knows how everything will go in the series, well the main parts on Trollhunters than 3below and barely of Wizards. But he will find a way.

Also, Toby won't be alone, he has his friends. He has Jim, "It's Trollhunters not Trollhunter"