The correct form to fill in the blank is "will issue."

So the complete sentence would be:
"Judging from past experience we can expect that encouraging news will issue from time to time."

### Explanation:
- **"will issue"** is used here to indicate a future action that is expected to occur. In this context, "issue" means to come out or be released.
- The sentence discusses a prediction based on past experiences, which is why the future simple tense ("will") is appropriate.

This usage shows that, like in the past, we anticipate that encouraging news will continue to come out in the future.