What he really means is it's only a guess.
—What he really means is it’s only a guess.—
...on the precise timing. He’s saying it is a “when” thing, not “if”, and it is not years away. It is a short term thing.
Think of it as a “five day forecast” sort of thing. If the weatherman is predicting hard rain for three of the next five days and “showers” for the other two, it is probably not a good week to plan a picnic. Probably...