I think there's a chance. The manga is full of surprises, and a new conflict that involves Thorfinn fighting could arise to add more excitement and drama to the story.
Thorfinn does fight again. The manga develops his character through various combat situations, each presenting different obstacles and opportunities for growth.
Well, Thorfinn's strength in the manga is quite remarkable. Not only physically but also mentally. He overcomes numerous hardships, which makes him stronger in various aspects.