Answer:
Chris had a premonition of what might happen
Explanation:
There is nowhere in the book that shows that Chris was suicidal or had a wish to die. He was downcast and unsure of his return because of his high unpreparedness for his adventure to the Alaskan wilderness. This is not the only dangerous event that Chris had undertaken, he only foresaw the danger in this coupled with his ineffective preparation for the journey.
"This is the last you shall hear from me Wayne. Arrived here 2 days ago. It was difficult to catch rides in the Yukon Territory. But I finally got here. Please return all mail I receive to the sender. It might be a very long time before I return south. If this adventure proves fatal and you don't ever hear from me again, I want you to know you're a great man. I now walk in the wild."
From this letter, we could see that Chris still saw a possibility of return, though slim. "It might be a very long time before I return south", this is enough evidence that he had no plan to kill himself, he only foresaw impending fatality in the adventure which may cause the wilderness to see his end.
