I’ve decided to assign numbers to some of the sentences in this thread for easier reference: 8)
1. Sooner or later we will have to make a tough decision.
2. We will yet have to make a tough decision.
3. We have yet to make a tough decision.
Here’s my take on things:
Sentences 1 and 2 have the same meaning.
Sentence 3 has a different meaning, but it is a more typical sort of sentence than Sentence 2.
Sentences 1 and 2 both anticipate that there will be a tough decision to make in the future. Sentence 1 is the more typical way to express this idea.
Sentence 3 states that there have been no tough decisions in the past. It does not suggest any anticipation of a tough decision in the future.