The hearer's linguistic experience affects anticipation. In poetry, knowing the rhyme consonant (rawī) may greatly narrow the expected ending. Without it, the sense may still direct the listener, although more than one completion could remain possible.
When ikhtalafū (they differed) has appeared earlier in a discussion of ongoing disagreement, an ending such as yakhtalifūn may seem particularly apt. Yet no rule says the meaning must always force exactly one final lexical item.
The criterion is strong contextual preparation, not a claim that every listener can infallibly predict every closure.